Related Clues:

• Like an excellent guard dog
• On top of things
• Not drowsy
• Word with red or on
• Observant
• Red state?
• Like a worthy watchdog
• 'Nevermore' speaker
• Having heightened senses
• See 109-Across, with 'The'
• NFL player with a black helmet
• APB, for one
• A serious one may be red
• Storm warning
• Emulate Paul Revere