Related Clues:

• Warn
• Vigilant
• Review
• See 10-Down
• Parting of the heavens, maybe
• On one's toes
• Verne character moving against the tide?
• Seer's sign
• Like Argus
• Warning sign
• On edge
• Telltale sign
• Ready to react, perhaps
• Make aware
• Sign of things to come