Silly aspect to debts (9)

I believe the answer is:

facetious

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'silly' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?

'aspect to debts' is the wordplay.
'aspect' becomes 'facet' (synonyms).
'to debts' becomes 'IOUs' (promises to pay debts).
'facet'+'ious'='FACETIOUS'

Can you help me to learn more?

(Other definitions for facetious that I've seen before include "Flippant, frivolous" , "Tongue-in-cheek" , "Intended to be amusing or witty" , "Jocular; frivolous" , "Inappropriately humorous" .)

I've seen this clue in The Daily Express.

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