Creature in another nest (4)
I believe the answer is:
erne
'creature' is the definition.
(erne is a kind of creature)
'in another nest' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ERNE' is hidden in the letters of 'another nest'.
(Other definitions for erne that I've seen before include "Large bird" , "Irish river, loughs; sea bird" , "Flier" , "Lough of the North" , "River and lake of the North" .)