Group of three musicians (4)
I believe the answer is:
trio
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">group of three musicians</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 trio that I've seen before include "A group or set of three" , "Piece for three players" , "Work for three" , "Beethoven's 'Archduke', for instance" , "Threesome" .)