Raven's call (3)
I believe the answer is:
caw
'raven's call' 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" , "Call like rook" , "Crow's cry" , "Rook's call" .)