An American, to the French, is athletic (5)

I believe the answer is:

agile

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'athletic' is the definition.
(I've seen this before)

'an american to the french' is the wordplay.
'an' becomes 'a'.
'american' becomes 'gi' (I can't explain this - if you can you should believe this answer much more).
'to the french' becomes 'le'.
'a'+'gi'+'le'='AGILE'

'is' is the link.

Can you help me to learn more?

(Other definitions for agile that I've seen before include "Quick in movement" , "alert" , "Nimble, supple" , "Quick-moving, supple" , "Nimble on the feet" .)

I've seen this clue in the Evening Standard.

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