Possible Clues:

• Franz ..... composed ` `The Merry Widow' '
• Hungarian composer Franz
• Franz ..... composed 'The Merry Widow'
• "The Count of Luxembourg" operettist Franz
• "Merry Widow" composer
• Backing producer of Joseph caught out composer
• Old king touring hospital to find composer
• Operetta composer Franz
• Franz -, The Merry Widow composer
• Composer cut singer short: sorry for interrupting!