Made waves on finding the account unpaid (8)

I believe the answer is:

billowed

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'made waves on finding' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Maybe there's a link between them I don't understand?

'the account unpaid' is the wordplay.
'the account' becomes 'bill' (synonyms).
'unpaid' becomes 'owed' (similar in meaning).
'bill'+'owed'='BILLOWED'

Can you help me to learn more?

(Other definitions for billowed that I've seen before include "Flowed with an undulating motion; filled with air" , "Swollen account was due payment" , "was swelling" .)

I've seen this clue in the Evening Standard.

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