Masterstroke (4)
I believe the answer is:
coup
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">masterstroke</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for coup that I've seen before include "revolution?" , "Brilliant and notable success" , "A successful action or revolt" , "Sudden change, illegally or by force" , "Successful exploit or action" .)