Possible Clues:

• Much-requested Italian song
• Basis of the song 'It's Now or Never'
• Song whose opening lyric translates to 'What a beautiful thing is a sunny day'
• Only in sacred mantra, I love traditional Neapolitan song
• Neapolitan song used to sell Cornettos?
• Italian encore song, often
• Neapolitan song whose first line translates to 'What a beautiful thing is a sunny day!'
• This tuned rendering melodious note?
• Single note in old, old song
• Pavarotti standard whose name means 'My Sunshine'