Right Now I am using this keys [Space]+ [Alt][Space]+[N] to pause the video & also minimize the vlc.
Is it possible to pause & minimize the video in vlc by single key?
As for your question, you can assign a "Boss key" in [Tools→Preferences—Hotkeys]. It minimizes VLC to the system tray + stops playback.
On a related note, as I found this discussion while looking for a solution to a similar but not identical problem. Maybe it'll help someone.
There is a workaround if you use a script. For example, I use a mouse gesture software (StrokesPus.net) and wanted to minimize VLC to the system tray without my music stopping with a gesture. (I think you can do that with a macro as well, then assign such macro to a keyboard button.)
For that, I first assigned a [Boss Key] in VLC settings in [Tools→Preferences—Hotkeys] ("Esc" in my case, instead of "Exit full screen", as you can exit it by double clicking). Then I also assigned a global [Play / Pause] combination ("Fn" + "F7" in my case). Then, I activated the script record function in StrokesPus.net and pressed "Esc", then "Fn" + "F7". You will have pauses between keystrokes; if you want your script to execute in full immediately, you'll need to set those pauses to the minimum value.
If someone's interested, you can find the code for my script — I think it's Java? Not sure — that works for me in StrokesPlus.net here (I can't have multiple lines for some reason): https://forum.videolan.org/viewtopic.php?f=14&t=158859&p=529706#p529706