It's been a long time since I have seen _Bell, Book, and Candle_; actually,
I last saw it at a drive-in theater with my parents when it came out!
I didn't remember the French singer in the movie, but I thought a reference
book might list him.  Sure enough, _The Motion Picture Guide_ credits
Phillipe Clay as French Singer.
 
Kristine Brancolini
Indiana University Libraries