Jock's counterpart (4)
I believe the answer is:
nerd
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">jock's counterpart</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 nerd that I've seen before include "Someone boring (about computers?)" , "one that's overly cerebral" , "Socially inept but knowledgeable person" , "Obsessive," , "Flag on poles; wide (headline)" .)