Sound made when crowing? (3)
I believe the answer is:
caw
This clue is a double definition.
'sound' is the first definition.
(caw is a kind of sound)
'crowing?' is the second definition.
(I know that crowing can be written as caw)
'made when' acts as a link.
(Other definitions for caw that I've seen before include "Rook's cry" , "Harsh cry of a crow" , "Cry of a rook" , "Crow's cry" , "Rook's call" .)