Patent dispute one challenges in court (9)

I believe the answer is:

plaintiff

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'one challenges in court' is the definition.
I can't tell whether this defines the answer.

'patent dispute' is the wordplay.
'patent' becomes 'plain' (synonyms).
'dispute' becomes 'tiff' (tiff is a kind of dispute).
'plain'+'tiff'='PLAINTIFF'

Can you help me to learn more?

(Other definitions for plaintiff that I've seen before include "Claimant" , "Person initiating lawsuit" , "accusing person in suit" , "Complainant" , "Person bringing a case against another" .)

I've seen this clue in The Sunday Times and The Times.

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