Opera tune (4)
I believe the answer is:
aria
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">opera tune</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for aria that I've seen before include "Repeated strain" , "selection of opera" , "Vocal solo in a cantata etc" , "Song, one from 'West Side Story' needing no introduction" , "Elaborate accompanied song for solo voice" .)