Related Clues:

• Good thing to sing in
• He wrote "Defence of Fort M'Henry"
• One that locks
• Of paramount importance
• Maxwell Anderson's was broad and slow
• Lock opener; low island
• --- To My Life (Boyzone)
• Lock undoer
• One making sense of partly scanty letters?
• Typewriter button, isle
• Eg, Ctrl, Alt or Esc
• Opener's locker
• Bit of a black eye? It can open
• Lock opener; island
• Codebreaker