Fictional bouncer admits right initiate (7)
I believe the answer is:
trigger
'initiate' is the definition.
(I know that trigger is a more specific form of the action initiate)
'fictional bouncer admits right' is the wordplay.
'fictional bouncer' becomes 'tigger' (I've seen this before).
'admits' means one lot of letters goes inside another (to admit is to allow in).
'right' becomes 'r' (common abbreviation).
'tigger' going around 'r' is 'TRIGGER'.
(Other definitions for trigger that I've seen before include "Initiate" , "Start" , "arm with this?" , "Lever on gun" , "Lever to activate firing mechanism" .)