Tennis's "King of Clay" (5)
I believe the answer is:
nadal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tennis's king of clay</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 nadal that I've seen before include "Top tennis player" , "Star with a 30 [RACKET]" , "Rafael __, Spanish tennis player" , "court figure" , "tennis champion" .)