Sentence:  "My misfortunes all began in wagging, Sir; but what could I do, exceptin' <WSD>wag</WSD>?" "Excepting what?" said Mr. Carker. "<WSD>Wag</WSD>, Sir. Wagging from school." "Do you mean pretending to go there, and not going?" said Mr. Carker. "Yes, Sir, that's wagging, Sir." 
Meaning of the word marked with <WSD> tags:  To play truant from school.