knuckle down
Intermediate (B1)informal
To stop messing around and work really hard.
"If you want to pass your exams, you're going to have to knuckle down and study."
Hear it in context
How Difficulty Turned DOOM into an RPG
Adam Millard - The Architect of Games · 12:40
You just have to knuckle down and solve it.
Wizard School, Part 2 | S1 E14 | Full Episode | Wizards of Waverly Place | @disneychannel
Disney Channel · 8:27
I SUGGEST YOU KNUCKLE DOWN AND GO TO THE LIBRARY.
How do you keep 8,995 codebreakers secret?
Tom Scott · 25:58
But I’m sure if we were again, people would knuckle down quite quickly.