Dressing bird with last of stuffing (6)
I believe the answer is:
robing
'dressing' is the definition.
(robing is a kind of dressing)
'bird with last of stuffing' is the wordplay.
'bird' becomes 'robin' (robin is a kind of bird).
'with' says to put letters next to each other.
'last of' suggests the final letters.
The last letter of 'stuffing' is 'g'.
'robin'+'g'='ROBING'
(Other definitions for robing that I've seen before include "dressing up" , "clothing" .)