Noisy revelling — endless feature of funfair (7)
I believe the answer is:
carouse
'noisy revelling' is the definition.
'endless feature of funfair' is the wordplay.
'endless' means to remove the last letter.
'feature of funfair' becomes 'carousel'.
'carousel' with its last letter taken off is 'CAROUSE'.
(Other definitions for carouse that I've seen before include "Drink a lot" , "booze" , "Drink freely and noisily" , "Party noisily" , "Roister" .)