Strip is a French gown (7)
I believe the answer is:
undress
'strip' is the definition.
(I know that strip can be written as undress)
'a french gown' is the wordplay.
'a french' becomes 'un' ('a' in French).
'gown' becomes 'dress' (gown is a kind of dress).
'un'+'dress'='UNDRESS'
'is' acts as a link.
(Other definitions for undress that I've seen before include "Disrobe - uniform for ordinary occasions" , "Nudity" , "Remove clothes, strip" , "Take one's clothes off" , "Sunders (anag)" .)