Soprano voice (6)
I believe the answer is:
treble
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">soprano voice</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 treble that I've seen before include "Threefold - singing voice" , "bet?" , "High darts score" , "Three times - a boy soprano" , "Multiply by three - high-pitched" .)