Crossword Genius

Stupid man wiped out in financial failures (5)

Ross

I believe the answer is:

crass

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'stupid' is the definition.
(I've seen this in another clue)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for crass that I've seen before include "Unrefined" , "Insensitively stupid" , "Grossly stupid, tactless" , "Showing gross lack of sensitivity" , "Tactless, boorish" .)

I've seen this clue in The Independent.
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