Unaccompanied song in several parts (8)
I believe the answer is:
madrigal
'unaccompanied song in several parts' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for madrigal that I've seen before include "Part-song" , "air" , "Without exaggeration" , "Part song for unaccompanied voices" , "glee" .)