Cry of bird — motherless one? (3)
I believe the answer is:
caw
'cry' is the definition.
(caw is a kind of cry)
I don't understand how the remainder of the clue works.
(Other definitions for caw that I've seen before include "Cry of a rook" , "Rook's cry" , "Rook's call" , "Crow's call" , "Harsh cry of a crow" .)