Related Clues:

• Like a watchdog
• All-points bulletin
• In a post-caffeine state
• Like good guards
• All-points bulletin, e.g.
• Eagle-eyed
• Standing at the ready
• Sign word that may be followed by an exclamation point
• Shout "heads up!"
• Paying heed
• "Heads up!" e.g.
• All eyes and ears
• It's high when it's red
• Attentive to possible danger
• Bright eyed and bushy tailed