Related Clues:

• Lady Antebellum, e.g
• Piece for three
• Three-person band
• Quartet with one out sick?
• Pair plus one
• Curly, Larry and Moe, e.g
• Folk music's Kingston __
• Common musical chord
• The Little Pigs, e.g
• Group of three singers
• The Jonas Brothers, e.g
• The Musketeers, e.g
• Maroon 5, if two members were crushed by a piano (hey, a guy can dream)
• The Police, e.g
• Somewhat vitriolic, categorising some musicians