Rook's cry (3)
I believe the answer is:
caw
'rook's cry' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for caw that I've seen before include "Crow's call" , "Harsh cry of a crow" , "Cry of a rook" , "Sound made by a crow, say" , "Rook's cry" .)