Wiktionary
adv. (context idiomatic English) hard at work. n. (context idiomatic after ''keep, put, have, hold (one's)'' English) (non-gloss definition: used for form idioms meaning "to work hard, or focus heavily on work.")
Usage examples of "nose to the grindstone".
He girds his loins, squares his shoulders, and with a smile on his lips, a glint in his eye, his feet on the ground, his head in the clouds, his back to the wall, a song in his heart and a spring in his step, puts his nose to the grindstone and lets George do it.
And when I get back I want to see you with your shoulder to the wheel and your nose to the grindstone.
In the socialist state everybody will have to keep his feet flat on the floor, his head in the clouds, his shoulder to the wheel, his back to the wall, his ear to the ground, and his nose to the grindstone.
What do you suppose that, having once placed my shoulder to the wheel and my nose to the grindstone, I will leave the furrow unplowed?
He's got to leave troops there to keep Urban's nose to the grindstone, and still a lot of people are going to think their consciences are free of any kind of obedience.
Through the remainder of the decade, John Campbell kept my nose to the grindstone and made sure he got additional Foundation stories.
George is right, Pancho's had her nose to the grindstone ever since she came up here.
I keep my nose to the grindstone and gnaw the dry crust which God gave me.