The French girl is permissible (5)
I believe the answer is:
legal
'permissible' is the definition.
(I've seen this in another clue)
'the french girl' is the wordplay.
'the french' becomes 'le' ('the' in French).
'girl' becomes 'gal' ().
'le'+'gal'='LEGAL'
'is' acts as a link.
(Other definitions for legal that I've seen before include "Constitutional" , "associated with silk business?" , "not banned" , "not breaking the law" , "Like some tender" .)