Rowing crew fed noisily (5)
I believe the answer is:
eight
'rowing crew' is the definition.
(crew of eight rowers)
'fed noisily' is the wordplay.
'fed' becomes 'ate' ('eat' can be a synonym of 'feed').
'noisily' indicates a 'sounds like' (homophone) clue.
'ate' is a homophone of 'EIGHT'.
(Other definitions for eight that I've seen before include "4 x 2" , "What's next?" , "Number (of oarsmen?)" , "Set of rowers" , "destroyed [IN 8A] here!" .)