Slowly (6)
I believe the answer is:
adagio
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">slowly</span>' is the definition.<br/ ><span class="explanation-format__explanation">(musical term)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for adagio that I've seen before include "(A movement) to be played slowly" , "Slow musical passage" , "Slowly and graceful, in music" , "moving slowly" , "In slow time (music)" .)