Tastelessly showy (6)
I believe the answer is:
flashy
'tastelessly showy' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for flashy that I've seen before include "Gaudy or showy" , "Superficially brilliant" , "Cheap and showy" , "Showily stylish" , "Showy but empty; Has fly (anag.)" .)