Sumptuousness (8)
I believe the answer is:
opulence
'sumptuousness' is the definition.
(I know that sumptuousness can be written as opulence)
This is the entire clue.
(Other definitions for opulence that I've seen before include "Ostentatious wealth" , "State of affluence and luxury" , "Impressive richness" , "State of wealth or abundance" , "Wealth, luxury" .)