Word in the etymology of "checkmate" (4)
I believe the answer is:
shah
'word in the etymology of checkmate' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for shah that I've seen before include "Persian emperor" , "Former Iranian monarch" , "Sovereign ousted in 1979" , "Old king" , "Persian king" .)