Related Clues:

• Vigilant
• See 10-Down
• 'Hey, buddy!'
• 'Over here!'
• On one's toes
• Like Argus
• This will get your attention
• It may precede the sharing a of secret
• On edge
• Ready to react, perhaps
• ''Listen!''
• Furtive summons
• Make aware
• 'Look over here!'
• Wide awake