Answer: rectifies

AnswerCrossword Clue
rectifiesPurify or refine (a substance), esp. by repeated distillation
rectifiesPut (something) right; correct
rectifiesRECTIFY, to correct (to make right (in accordance with what is true and fitting))
rectifiesConvert (alternating current) to direct current
rectifiesFind a straight line equal in length to (a curve)