Possible Clues:

• See 17
• Person who can sing, except for one bad note
• Forbid it with a single voice
• Where one might get Bass and with it one that isn't Bass, by the sound of it
• Under ten, or this invoice?
• A singer, a Brit, unhappily single
• Singer, with a single exception, accepting Italian
• Merrill's range
• Pub has appeal to individual singer
• Exclude it, one invoice, perhaps