Hock a piece on board (4)
I believe the answer is:
pawn
This clue is a double definition.
'hock' is the first definition.
(I know that hock can be written as pawn)
'a piece on board' is the second definition.
(I've seen this before)
(Other definitions for pawn that I've seen before include "piece on board" , "Chessman often sacrificed" , "Lend uncle" , "Deposit as pledge" , "a future queen, possibly" .)