Related Clues:

• Trouble indicator
• Engage in pugilism
• Not dozing
• Trade jabs
• Not nodding
• 'Look out below!,' e.g.
• Awake and aware
• Having pricked ears
• Keen-eyed
• Duke it out
• Swing in the ring
• Like watchmen
• Word with music or sand
• Paying attention
• Indulge in fisticuffs