Cry of a sheep (3)
I believe the answer is:
baa
'cry of a sheep' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for baa that I've seen before include "Bleat of a sheep" , "Statement from those flocking" , "Sheep's bleat" , "not quite consistent set of good A-level results?" , "Call from Jacob" .)