Answer: slaving

AnswerCrossword Clue
SLAVINGWorking like a dog
SLAVINGHard on the job
SLAVINGActivity for Spartacus in 74 B.C.
SLAVINGHard at it
slavingenslave
slavingSLAVE, to work like a drudge
slavingtraffic in slaves
slavingwork like a slave drudge
slavingmake directly responsive to another mechanism