Sumptuously rich (6)
I believe the answer is:
lavish
'sumptuously rich' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lavish that I've seen before include "Plentiful, generous" , "Unstinting" , "Plentiful or munificent" , "Luxurious" , "Profusely generous" .)