Related Clues:

• Peter, Paul & Mary, e.g.
• Group of three
• Kingston, e.g.
• 17-Across
• Quartet when one's out sick
• It's short of a quartet
• See 70-Across
• Quartet minus one
• Pod opener?
• Destiny's Child, e.g.
• Head of state?
• Lounge group, maybe
• Angle lead-in
• Kingston, for one
• Bee Gees or The Stooges, e.g.