Superconductor? (7)
I believe the answer is:
maestro
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">superconductor?</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for maestro that I've seen before include "ace" , "Eminent musician" , "Gifted performer" , "conductor, maybe" , "best in field" .)