GI mixed with umpteen characters socialising (7,2)

I believe the answer is:

meeting up

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'characters socialising' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'gi mixed with umpteen' is the wordplay.
'mixed with' is an anagram indicator.
'gi' anagrammed with 'umpteen' gives 'MEETING UP'.

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I've seen this clue in The Daily Express.

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