Short underwear is more flashy (8)
I believe the answer is:
brassier
'more flashy' is the definition.
('brassy' can be a synonym of 'flashy')
'short underwear' is the wordplay.
'short' means to remove the last letter.
'underwear' becomes 'brassiere'.
'brassiere' with its final letter taken off is 'BRASSIER'.
'is' is the link.
(Other definitions for brassier that I've seen before include "Louder" , "More shamelessly bold" , "More blaring" , "More bold and vulgar in metallic way?" .)