Chicken in the nest (3)
I believe the answer is:
hen
'chicken' is the definition.
(hen is a kind of chicken)
'in the nest' is the wordplay.
'in' indicates a hidden word.
'HEN' can be found hidden inside 'the nest'.
(Other definitions for hen that I've seen before include "Laying bird" , "Female bird" , "Adult female chicken" , "Not cock" , "Female lobster, fowl" .)