Piece that gets checkmated (4)
I believe the answer is:
king
'piece that gets checkmated' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for king that I've seen before include "Male royal" , "Chesspiece which mustn't be lost" , "Card, draughts piece" , "Supreme ruler" , "See 23 Down" .)