Repealed contribution to code I fill under review (9)

I believe the answer is:

nullified

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'repealed' is the definition.
Although both the answer and definition are past participle verbs, I don't see how they can define each other.

'contribution to code i fill under review' is the wordplay.
'contribution to' indicates the answer is hidden within the clue.
'review' is a reversal indicator.
'deifillun' can be found hidden inside 'code i fill under'.
'deifillun' reversed gives 'NULLIFIED'.

Can you help me to learn more?

(Other definitions for nullified that I've seen before include "revoked" , "Cancelled out" , "Made invalid" , "Abrogated" , "Scrubbed" .)

I've seen this clue in the Sydney Morning Herald.

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