Bellini opera (5)
I believe the answer is:
norma
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bellini opera</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for norma that I've seen before include "small group of stars" , "The 'Rule' constellation" , "Drawing instrument" , "Marilyn was properly one" , "name for Monroe" .)