Possible Clues:

• Love overseas
• Martin's "That's __"
• What makes il mondo go round?
• Love, in 17 Down
• Viola d'___
• Subject for Enrico Caruso
• Lombardy love
• ". . . ___ perfect union . . ."
• What that is, in a 1953 song
• '...like a big pizza pie, that's ___' (old song lyric)