Castle cheat? (4)
I believe the answer is:
rook
I believe this clue is a double definition.
'castle' is the first definition.
(synonyms)
'cheat?' is the second definition.
(I know that rook is a type of cheat)
(Other definitions for rook that I've seen before include "Rip off - bird" , "Man in game" , "man for moving" , "journalist Jean" , "Black bird - cheat - chess piece" .)