Sentence:  Foggier yet, and colder! Piercing, searching, biting cold. If the good Saint Dunstan had but nipped the Evil Spirit's nose with a touch of such weather as that, instead of using his familiar weapons, then indeed he would have roared to lusty purpose. The owner of one scant young nose, gnawed and mumbled by the hungry cold as bones are gnawed by dogs, stooped down at Scrooge's keyhole to regale him with a Christmas <WSD>carol</WSD>: but at the first sound of— / "God bless you merry gentleman! / May nothing you dismay!" / Scrooge seized the ruler with such energy of action, that the singer fled in terror, leaving the keyhole to the fog and even more congenial frost. 
Meaning of the word marked with <WSD> tags:  A (usually traditional) religious or secular song sung at Christmastime.