Fashionable inference to finish with (2,10)

I believe the answer is:

in conclusion

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'with' is the definition.
Both the definition and answer are adverbs. Maybe there's a link between them I don't understand?

'fashionable inference to finish' is the wordplay.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'inference' becomes 'conclusion' (conclusion is a kind of inference).
'to finish' means one lot of letters go next to another (some letters go after or 'finish' others).
'in'+'conclusion'='IN CONCLUSION'

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I've seen this clue in The Times.

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