Lively movement (7)
I believe the answer is:
scherzo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lively movement</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 scherzo that I've seen before include "Lively piece of music" , "Fast movement (music)" , "Fast movement of symphony" , "Lively passage" , "Light or playful movement" .)