Pieces of eight (6)
I believe the answer is:
octets
'pieces' is the definition.
(octet is a kind of piece)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for octets that I've seen before include "Groups of eight, often singers" , "groups of eight, say singers" , "Groups of eight peformers" , "Sets of eight" .)