Related Clues:

• Driving danger
• It's a great barrier
• Dorothy's last name, in 'The Wizard of Oz'
• Nautical hazard
• Cause of many an accident
• Nor'easter, e.g.
• River hazard
• Haze
• London weather, often
• Visibility problem
• Great Barrier --
• Navigation hindrance
• Naviga-tion hindrance
• Strong gust
• Outburst of laughter