Hi Alan,
Eleanor has beaten me with that suggestion!
Chambers has BEAN as a colloquial expression for the head; however, that answer doesn't solve the cryptic part of the clue. I have used the Unilingua search engine and a French-English dictionary, as I had to eliminate the construct of 'a French...' being 'un' or 'une'. I am no further forward. Apologies!
Best wishes,
Caravaggio