Pigeon's cry (3)
I believe the answer is:
coo
'pigeon's cry' is the definition.
'coo' can be an answer for 'cry' (coo is a kind of cry). I also know that 'pigeon' relates to this answer.
This is the entire clue.
(Other definitions for coo that I've seen before include "Dove's noise" , "Goodness me!" , "well I never!" , "(Of pigeon) murmur" , "I'm surprised" .)