hard at work

bone hard

As hard as a bone, rock hard.

busy work

Work or activity performed with the intention or result of occupying time, and not necessarily to accomplish something productive; routine work of low priority undertaken for the sake of avoiding idleness.

close enough for government work

Adequate; acceptable as government work, imperfect but not worth the time nor effort of improving.

cold hard cash

Money, regarded as an incentive that can override any doubts or ethical concerns.

crazy enough to work

Acknowledging that an idea, plan, or strategy seems foolish, implausible, or risky, yet might succeed precisely because of its unconventional or unexpected nature.

detective work

investigative research

die hard

Of a living being, to die only after a desperate struggle for life.

dirty work

One or more unpleasant tasks, assignments, or employment duties, especially those of a disreputable or illicit nature.