Jock (7)
I believe the answer is:
athlete
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">jock</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that jock can be written as athlete)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for athlete that I've seen before include "E.g. runner or jumper" , "gymnast, maybe" , "Track and field competitor" , "Competitive runner, e.g." , "One trains in sport" .)