Wonk (4)
I believe the answer is:
nerd
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wonk</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nerd that I've seen before include "Intelligent but single-minded expert" , "Feeble person (sl.)" , "Boring person" , "Anorak (informal)" , "one that's overly cerebral" .)