Related Clues:

• 'Yo!'
• See 11-Down
• 'Look here!'
• Letter opener
• Attention-getter
• Military address
• See 8-Down
• Word for a superior
• 'Hey there!'
• Title of respect
• Whispered call
• Elton John, e.g.
• 'Hey, Mac!'
• Elton John or Mick Jagger
• Knight, by definition