Chess castle (4)
I believe the answer is:
rook
'chess castle' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rook that I've seen before include "Gregarious black bird" , "Ringing in the ears" , "Man in game" , "Fleece - bird" , "Swindle (colloq.); bird" .)