Dove call (3)
I believe the answer is:
coo
'dove call' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for coo that I've seen before include "Murmur, speak softly" , "Speak lovingly -- cry softly" , "Speak fondly" , "Sound like a dove" , "Pigeon noise" .)