Related Clues:

• Attentive
• With ears pricked
• "Hey, Mac!"
• Not nodding
• "Listen!"
• Red flag, e.g.
• Command to a listener
• Prepared for action
• Secretive attention getter
• Caffeinated?
• Fence’s utterance
• Trouble indicator
• Quaint cry
• 'Hey, over here!'
• Not dozing