Ostentatiously rich (7)
I believe the answer is:
opulent
'ostentatiously rich' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for opulent that I've seen before include "extremely elegant" , "'Rich, sumptuous (7)'" , "Ostentatiously costly and luxurious" , "Moneyed" , "Wealthy, got lots of money" .)