Answer: icedup

AnswerCrossword Clue
ICEDUPFrozen over
ICEDUPLike some winter windshields
ICEDUPBecame slick
ICEDUPGot frosty
ICEDUPSlick, in a way
ICEDUPBecame a winter hazard, as a road
ICEDUPNeeded a coating of heated propylene glycol, say
ICEDUPJammed, in a way
ICEDUPFrosted
ICEDUPFroze
ICEDUPGot frozen
ICEDUPFrost-covered
ICEDUPGot dangerous, as a road, perhaps
ICEDUPFroze over
ICEDUPBecame dangerous to drive in December
ICEDUPFroze solid
ICEDUPNeeding defrosting
ICEDUPGot slick
ICEDUPAcquired a slick coat