Parisian having a fling with his girlfriend? (6)

I believe the answer is:

apache

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'parisian having a fling with his girlfriend?' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

This is all the clue.

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(Other definitions for apache that I've seen before include "North American native tribe" , "N American Indian tribe or old Paris ruffian" , "Indians" , "ruffian in capital of France" , "Hooligan in Paris" .)

I've seen this clue in the Evening Standard.

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