Feature of bird stuffed by artist (5)
I believe the answer is:
trait
'feature' is the definition.
(I've seen this before)
'bird stuffed by artist' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'stuffed by' is an insertion indicator (stuff can mean to fill or insert into).
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'tit' enclosing 'ra' is 'TRAIT'.
'of' is the link.
(Other definitions for trait that I've seen before include "Distinguishing feature" , "Characteristic or distinguishing quality" , "Mannerism" , "Attribute, characteristic" , "Quirk" .)