Possible Clues:

• “As they say in old ___, c’est la vie, c’est la vie” (Sarah Vaughan lyric)
• "You Don't Know —" (Cole Porter song)
• "Gay" city in a Cole Porter tune
• 'Gay' city in a Porter song
• “La Belle ___” (revue that launched Al Jolson’s career)
• 'Gay' city in a Cole Porter song
• 'Gay' capital of song
• French capital, slangily
• 'Gay' French city of a Cole Porter song
• European capital, informally