Wealth is wonderful (7)
I believe the answer is:
capital
I believe this clue is a double definition.
'wealth' is the first definition.
(I've seen this before)
'wonderful' is the second definition.
'is' acts as a link.
(Other definitions for capital that I've seen before include "Major city - investment - great!" , "Chief; excellent" , "Seed money" , "Money available to produce interest" , "Money saved or invested - seat of government" .)