Joins others in Maine, upset after rigging (5,2)

I believe the answer is:

meets up

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'maine upset after rigging' is the definition.
I know nothing about this answer so I can't judge whether this works.

'joins others' is the wordplay.
'joins' becomes 'meets' (meeting is a kind of joining).
'others' becomes 'up' (I can't explain this - if you can you should believe this answer much more).
'meets'+'up'='MEETS UP'

'in' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.

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