Unaccompanied song in several parts (8)
I believe the answer is:
madrigal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unaccompanied song in several parts</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 madrigal that I've seen before include "Part-song" , "air" , "Without exaggeration" , "Part song for unaccompanied voices" , "glee" .)