get one's hands dirty

verb1

1. •
   To get involved with the unpleasant parts of a task, such as manual labor or unethical activities.

   • If you expect to seal up every possible source of draftiness, you'll have to get your hands dirty — there will be some kneeling and crawling involved.
   • He doesn't get his hands dirty — that's what the henchmen and the plausible deniability are for.