Initially, banana skin repelled censor (5)
I believe the answer is:
bleep
'censor' is the definition.
(as in bleeping a swearword)
'initially banana skin repelled' is the wordplay.
'initially' says to take the initial letters.
'skin' becomes 'peel' (synonyms).
'repelled' says the letters should be written backwards.
The first letter of 'banana' is 'b'.
'peel' written backwards gives 'leep'.
'b'+'leep'='BLEEP'
(Other definitions for bleep that I've seen before include "Page" , "(Alarm) pulse" , "Sharp electronic sound" , "Electronic signal calling a person" , "Make short shrill signalling sound" .)