He helped one going round before fellows left (6,3)

I believe the answer is:

headed off

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'fellows left' is the definition.
The answer and definition can be both to do with social activities as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?

'he helped one going round before' is the wordplay.
'helped' becomes 'aided' ('aid' can be a synonym of 'help').
'one' becomes 'i' (Roman numeral).
'going' is a deletion indicator.
'round before' becomes 'off' (I can't justify this - if you can you should believe this answer much more).
'aided' with 'i' taken away is 'aded'.
'he'+'aded'+'off'='HEADED OFF'

Can you help me to learn more?

I've seen this clue in The Guardian.

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