Duo quadrupled (5)
I believe the answer is:
octet
'duo quadrupled' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for octet that I've seen before include "Group of eight musicians" , "Played" , "A group of eight, may be singers" , "Medieval Latin hymn" , "Musical composition for eight performers" .)