Proper Liberal went first and fought for his honour (7)

I believe the answer is:

duelled

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'fought for his honour' is the definition.
The definition suggests a singular noun but the answer is not.

'proper liberal went first' is the wordplay.
'proper' becomes 'due' (I've seen this before).
'liberal' becomes 'l' (abbreviation).
'went first' becomes 'led'.
'due'+'l'+'led'='DUELLED'

'and' acts as a link.

Can you help me to learn more?

(Another definition for duelled that I've seen is " Fought, even to death".)

I've seen this clue in The Guardian.

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