Bird coming back in the winter, generally (5)
I believe the answer is:
egret
'bird' is the definition.
(I know that egret is a type of heron)
'coming back in the winter generally' is the wordplay.
'coming back' says the letters should be written in reverse.
'in' indicates the answer is hidden within the clue.
'terge' is hidden within 'winter generally'.
'terge' back-to-front is 'EGRET'.
(Other definitions for egret that I've seen before include "Long-plumed heron" , "White wading bird" , "One wading" , "Wading bird like a heron" , "Type of forty eight Ac" .)