Possible Clues:

• Winter driving hazard
• An unseen hazard to 1 10, perhaps British need reserve
• Driving hazard in Belgium around the French border at Chimay first of all kept in check
• Hard-to-see transparent hazard
• Winter driving hazard ... or a literal hint to four squares in this puzzle
• Dangerous road coating
• Be a click away from dark pathway hazard
• Hard-to-see hazardous road condition (2 words)
• Winter road hazard
• Ban hard water -- it can be dangerous