Cheat on the board (4)

I believe the answer is:

rook

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'cheat' is the definition.
(I know that rook is a type of cheat)

I cannot understand how the rest of the clue works.

(Other definitions for rook that I've seen before include "Castle -- bird" , "Chess piece or crow" , "Gregarious black bird" , "Use deceit to get money" , "A bird; overcharge" .)

I've seen this clue in The Globe and Mail.

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