Competitive rider (7)
I believe the answer is:
eventer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">competitive rider</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for eventer that I've seen before include "Competing horse or rider" , "Equestrian competitor" , "Equestrian horse" , "Showjumper" , "Competitive horse/rider" .)