Related Clues:

• Lacking 56-Across
• Soprano's big number
• Cantatrice's offering
• 57 Down solo
• Verdi specialty
• ''Turandot'' solo
• Song for Callas
• "Summertime," for one
• Caruso solo
• Scotto solo
• Bravura solo
• Recital selection
• A song for one
• Soprano's song, perhaps
• Piece for Pinza