Sentence:  Quelling his nerves, Moist grabbed a <WSD>jim crow</WSD> and opened the trap door on to the roof of the guard's van, to the initial amazement of the grag who had been trying to force his way in. 
Meaning of the word marked with <WSD> tags:  A tool for bending railway rails, by holding the rail with two arms and pushing a screw into the other side.