Gregarious bird (8)
I believe the answer is:
starling
'gregarious bird' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for starling that I've seen before include "Gregarious songbird" , "Might Gran list badly for the bird" , "Passerine bird" , "Dark, glossy bird" , "is naturally a good mimic" .)