Cryptic crossword (jigsaw fill)

Question

This is a cryptic crossword jigsaw fill: the clues are listed below, grouped by length (the only clues to have length in the standard parentheses are those having two words) and in alphabetical order in each group. When they are solved they can be arranged to fit in the grid in exactly one way.

Once the grid is filled, the numbered squares will spell out, in order, the expected (though fictional) feminine noun for a member of a famous group. Solvers should correct the spelling (change exactly one letter) to be the name of the group (this will produce real words in the grid, though arguably one of them is oxymoronic). Solvers should also highlight three surnames in the grid, of members of the group, and indicate which single letter should be changed elsewhere in the grid to find a fourth surname (sadly this change does not create real words).

3 Letters

 Design a current for Malta
 Tropical bird nests in Madagascan ironwood

4 Letters

  Dye a duck
  Half a square metre of paper is perfect! (1-3)
  Schematic's second page missing a key...
  ...tone, for example, laid out
  Last two thirds of push for small defense
  No second impact to back of knee
  Edmund's white with age and Henry's rather less masculine
  My intention broadcast by Man, for example
  Once illuminate starting letters in manuscript notes
  Indian gardener -- bad one
  Friar's opposite is mostly Capuchin
  State occupied with Frozen Snowman
  Dialect once supported by saint
  No mate for milky white gemstone?
  Local leftovers rot badly, son
  After seconds of spiced cake, essay Stilton

5 Letters

  High priest sets volcanic rock above man
  American paid up for desired missing wife
  A psi-sigma initial segment defines greatest orbital distance from centre
  (Informal) Sound of car maker getting nothing
  Demeter covers with wax...
  ...time after time, O Muse!
  Lots of LA hormone takes Venetian to height of poetic inspiration
  Stinking tide stirred up after most of reef is destroyed
  Carry back: private secretary swallows quickly
  Deflection into pocket -- Fagin offers a hiding place (2-3)
  Calibrate without outliers -- sign of balance
  US Saltpetre can reverse heading, right?
  Celtic letters found in 'Van Gogh -- a memoir'
  That woman, Vanessa, extremely indicates absence of vowel

6 Letters

  Debauched beasts; most, worthless
  Hobbesian companion?

7 Letters

  Like thin plates tangling right animal
  He examines and corrects reivers' discombobulation

10 Letters

  Trace of life essential for glowing particle (5,5)
  Parrot plague-host is iron-addled

Answer 1

The grid:

[

The group is

the OULIPO, a group of French experimental writers. The feminine noun is OULIPA. Correcting the latter to the former turns DIAL into DIOL and SPARK into SPORK (I'm not sure whether the intended oxymoron is SPORK itself -- spoon+fork -- or VITAL SPORK, since a spork is hardly vital).

Its members in the grid are

CALVINO, along the top; PASTIOR, down from the P near the end of the top row; MONK, at the bottom left. The one that needs changing is AUDIN, obtained by changing O to N in AUDIO near the bottom left. (Which unfortunately kills Mr Monk, too.) Alternatively, you could change the L at the end of DIAL/DIOL into an N to get BENS reading upward. (The resulting entry could be Celine Dion, perfectly reasonable even if not exactly a word.) But I suspect the composer's intention is BRAFFORT, obtained by changing a K to an F on the right-hand side.

Individual solutions with explanations:

3 Letters

Design a current for Malta
Tropical bird nests in Madagascan ironwood

AIM (A+I+M)
ANI (substring: madagascANIronwood)

4 Letters

Dye a duck
Half a square metre of paper is perfect! (1-3)
Schematic's second page missing a key...
...tone, for example, laid out
Last two thirds of push for small defense
No second impact to back of knee
Edmund's white with age and Henry's rather less masculine
My intention broadcast by Man, for example
Once illuminate starting letters in manuscript notes
Indian gardener -- bad one
Friar's opposite is mostly Capuchin
State occupied with Frozen Snowman
Dialect once supported by saint
No mate for milky white gemstone?
Local leftovers rot badly, son
After seconds of spiced cake, essay Stilton

ANIL (A+NIL)
A-ONE (double definition)
CLEF (sChematic + LE(a)F)
DIAL (dial tone; LAID*)
FORT ((ef)FORT)
HOCK ((s)HOCK)
HORE (Edmund Spenser; it's an old spelling of HOAR; H+(m)ORE)
ISLE (sounds like I'LL; the Isle of Man)
LIMN (first letters of L(etters) I(n) M(anuscript) N(otes))
MALI (MAL+I)
MONK (MONK(ey))
OLAF (LA = Louisiana in OF = with)
ONST (ON+ST)
OPAL (O+PAL)
ORTS (ROT*+S)
PAST (second letters of sPiced cAke eSsay sTilton)

5 Letters

High priest sets volcanic rock above man
American paid up for desired missing wife
A psi-sigma initial segment defines greatest orbital distance from centre
(Informal) Sound of car maker getting nothing
Demeter covers with wax...
...time after time, O Muse!
Lots of LA hormone takes Venetian to height of poetic inspiration
Stinking tide stirred up after most of reef is destroyed
Carry back: private secretary swallows quickly
Deflection into pocket -- Fagin offers a hiding place (2-3)
Calibrate without outliers -- sign of balance
US Saltpetre can reverse heading, right?
Celtic letters found in 'Van Gogh -- a memoir'
That woman, Vanessa, extremely indicates absence of vowel

AARON (AA+RON)
ANTED (past tense of ANTE; (w)ANTED)
APSIS (initial segment of those words at start of clue)
AUDIO (AUDI+O)
CERES (double definition)
ERATO (ERA+T+O)
ESTRO (not sure about this; ESTRO(gen), LA implying American so e... rather than oe...? ESTRO means "inspiration" in Italian)
FETID ((ree)F+TIDE*)
GULPS (LUG< + PS)
IN-OFF (substring of fagINOFFers)
LIBRA ((ca)LIBRA(te))
NITER (TIN< + E + R -- thanks to @postmortes for correcting my first attempt at explaining this one, which wasn't what they'd intended and made less sense)
OGHAM (substring of vangOGHAMemoir)
SHEVA (SHE + V(aness)A)

6 Letters

Debauched beasts; most, worthless
Hobbesian companion?

BASEST (BEASTS*)
CALVIN (cryptic def referring to Bill Watterson's comics)

7 Letters

Like thin plates tangling right animal
He examines and corrects reivers' discombobulation

LAMINAR (RANIMAL*)
REVISER (REIVERS*)

10 Letters

Trace of life essential for glowing particle (5,5)
Parrot plague-host is iron-addled

VITAL SPARK (VITAL + SPARK)
ORNITHOSIS (HOSTISIRON*)