Bird from another nest (4)
I believe the answer is:
erne
'bird' is the definition.
(erne is a kind of bird)
'from another nest' is the wordplay.
'from' says the answer is hidden in the clue.
'ERNE' is hidden within 'another nest'.
(Other definitions for erne that I've seen before include "Sea bird: lough in Ulster" , "Eagle, river and lough" , "Sea-eagle in an Irish lake" , "White-tailed eagle" , "flyer in the main" .)