Gosh, is that a bird call? (3)
I believe the answer is:
coo
I believe this is a double definition.
'gosh' is the first definition.
'that a bird call?' is the second definition.
(I've seen this in another clue)
'is' acts as a link.
(Other definitions for coo that I've seen before include "Sound made by doves" , "Softly say" , "Call like a dove" , "(Of pigeon) murmur" , "well I never!" .)