Small shiny disc for decoration (6)
I believe the answer is:
sequin
'small shiny disc for decoration' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sequin that I've seen before include "Ballroom dancer's sewn-on sparkler?" , "Sparkling feature of ballroom dancing?" , "Shiny decorative disc" , "bright little thing" , "Italian gold coin" .)