Thieving bird (7)
I believe the answer is:
jackdaw
'thieving bird' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for jackdaw that I've seen before include "Crows relative" , "one found in crow's nest" , "Thieving bird" , "Grey-headed crow" , "Larcenous member of crow family" .)