Grey-headed crow (7)
I believe the answer is:
jackdaw
'grey-headed crow' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for jackdaw that I've seen before include "Small member of the crow family" , "Thief in Rheims" , "Small black crow" , "Grey-headed crow" , "Larcenous member of crow family" .)