Related Clues:

• Triad
• Musical group
• Beethoven's "Archduke," e.g.
• Three
• Rock's Green Day, e.g.
• Kingston --
• The witches in 'Macbeth,' e.g.
• Wooden shoe sailors, e.g.
• Andrews Sisters, e.g.
• Rock's Green Day, for one
• Small musical ensemble
• 'Pop, culture, TV' network
• Quartet with a defection
• ''The Three Tenors,'' for example
• Chamber-music group