Related Clues:

• Song sung singly
• 'In bad company,' per Ambrose Bierce
• Apart from a fifty-one?
• Have no co-pilot
• Play alone?
• Unchaperoned
• Pilot's milestone
• Friendless
• Flight school hurdle
• Note nothing without help
• See 26
• See 18
• See 7
• Molly's topless solo
• Unique shellfish sailor discarded