Related Clues:

• Trouble indicator
• Utter loudly
• Show you're 18-Across
• Not dozing
• "One for all and all for one," e.g.
• Not nodding
• Loud call
• 'Look out below!,' e.g.
• Sob
• Awake and aware
• Having pricked ears
• Keen-eyed
• Like watchmen
• Turn on the waterworks
• Paying attention