Answer: charks

AnswerCrossword Clue
charksto char; convert into coke
charksthe solid product resulting from the destructive distillation of coal in an oven or closed chamber or by imperfect combustion, consisting principally of carbon: used chiefly as a fuel in metallurgy to reduce metallic oxides to metals
charksthe carbonaceous material obtained by heating wood or other organic substances in the absence of air