Opposed to what in France is a period piece (7)
I believe the answer is:
antique
'a period piece' is the definition.
(piece or item from an earlier period)
'opposed to what in france' is the wordplay.
'opposed to' becomes 'anti' (anti means opposing something).
'what in france' becomes 'que' (I've seen this in another clue).
'anti'+'que'='ANTIQUE'
'is' acts as a link.
(Other definitions for antique that I've seen before include "Ancient object" , "Quite an old thing with age value" , "Item from an earlier time" , "Age-old" , "from long ago" .)