Answer: knuckledown

AnswerCrossword Clue
KNUCKLEDOWN

Get serious

KNUCKLEDOWN

Apply oneself earnestly

KNUCKLEDOWN

Get to work

KNUCKLEDOWN
Apply oneself to a task
KNUCKLEDOWN
Get serious about working
KNUCKLEDOWNApply oneself vigorously
KNUCKLEDOWNFloor scrubber's condition?
KNUCKLEDOWNGet serious at work or school