Tennis winner (3)
I believe the answer is:
ace
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tennis winner</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ace that I've seen before include "Playing card - expert" , "1" , "Expert; one" , "one among a set of diamonds" , "Tennis serve that the opponent can't reach" .)