Group of nine musicians (5)
I believe the answer is:
nonet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">group of nine musicians</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 nonet that I've seen before include "baseball team" , "group composition" , "Band's" , "Work for nine players" , "Composition for nine players" .)