Related Clues:

• Word on a dog-owner's sign, perhaps
• Sign of danger
• 'Heads up!'
• Be expectant
• Word of caution
• Hold on for
• Jabberwock advice
• Start of a sign on a gate
• Keep an eye out for
• Spooky warning
• ''Cave'' in ancient Rome
• Caveat word
• Stand in a queue for, say
• Lie in store
• 'Watch it!'