Child prodigy (10)
I believe the answer is:
wunderkind
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">child prodigy</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 wunderkind that I've seen before include "Child prodigy" , "One having early success" , "Perhaps Mozart" , "Clever young person" , "Extraordinary issue" .)