Provoke first of revellers to punch bouncer? (7)
I believe the answer is:
trigger
'provoke' is the definition.
'first of revellers to punch bouncer?' is the wordplay.
'first of revellers' becomes 'r' (1st letter of 'revellers').
'to punch' is an insertion indicator (some letters punch a hole in others).
'bouncer?' becomes 'tigger' (I've seen this before).
'r' placed inside 'tigger' is 'TRIGGER'.
(Other definitions for trigger that I've seen before include "Pull it to discharge gun" , "Gun-firing device" , "Set in motion - say gunfire" , "Activating device" , "Start" .)