Dressin' the bird (5)
I believe the answer is:
robin
This clue is a double definition.
'dressin'' is the first definition.
('robing' said like 'dressing' was; robing is a kind of dressing)
'bird' is the second definition.
(robin is a kind of bird)
'the' acts as a link.
(Other definitions for robin that I've seen before include "Seasonal bird" , "Christmas songbird" , "good fellow in the D [DREAM]" , "See 7" , "Famous outlaw" .)