Wealthy in a big way (3)

I believe the answer is:

fat

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'wealthy' is the definition.
(thesaurus)

I can't explain the rest of the clue.

(Other definitions for fat that I've seen before include "Portly" , "Greasy substance" , "Corpulent; little (chance)" , "and 24: Overpaid City type" , "Excess body weight" .)

I've seen this clue in the Evening Standard.

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