Christmas tree decoration (6)
I believe the answer is:
bauble
'christmas tree decoration' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bauble that I've seen before include "'Bead, trinket (6)'" , "Small cheap trinket" , "Showy but valueless ornament" , "worthless D [DECORATION]" , "Gaudy toy" .)