Crowd sound (4)
I believe the answer is:
roar
'crowd sound' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for roar that I've seen before include "Loud noise of angry bull" , "Lion's noise" , "Make loud angry sound like lion" , "Jaguar, for example, emits this" , "Lion's sound" .)