Part of feather, one for bird (5)
I believe the answer is:
heron
'bird' is the definition.
(heron is a kind of bird)
'part of feather one for' is the wordplay.
'part of' indicates a hidden word.
'HERON' can be found hidden inside 'feather one for'.
(Other definitions for heron that I've seen before include "Long-legged long-necked wading bird" , "Graceful grey bird with long neck" , "Large fish-eating bird" , "Large British wading bird" , "One bird" .)