Costume spangle (6)
I believe the answer is:
sequin
'costume spangle' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sequin that I've seen before include "Ballroom dancer's sewn-on sparkler?" , "Glittery decoration" , "small ornamental circle" , "Decorative spangle" , "Shiny piece to decorate garment" .)