Ostentatious clothes or decoration (6)
I believe the answer is:
finery
I believe this clue is a double definition.
'ostentatious clothes' is the first definition.
(I've seen this before)
'decoration' is the second definition.
(I have seen 'Ostentatious decoration ' mean 'finery' so perhaps 'decoration' could also mean 'finery')
(Other definitions for finery that I've seen before include "Elaborate clothing, jewellery etc" , "Elaborate clothes and accessories" , "Regalia" , "smart clothes" , "Ostentatious clothes" .)