Sheep call (3)
I believe the answer is:
baa
'sheep call' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for baa that I've seen before include "Sound from a ewe" , "Cry of lamb, sounds angry" , "Bleat of a sheep" , "Sound of sheep" , "not quite consistent set of good A-level results?" .)