Bird in the nest (3)
I believe the answer is:
hen
'bird' is the definition.
(I know that hen is a type of domesticated bird)
'in the nest' is the wordplay.
'in' says the answer is hidden in the clue.
'HEN' can be found hidden inside 'the nest'.
(Other definitions for hen that I've seen before include "Female bird" , "Coop resident" , "Clucking female" , "Domestic egg layer" , "Adult female chicken" .)