Wiktionary
vb. (context transitive English) To reduce the size of something by file (using the abrasive effects of a file).
Usage examples of "file down".
A rusty forties-style power mower appeared to be permanently parked in knee-high grass under lilac bushes at the edge of the yard, and a pear tree and a half dozen aging apple trees marched in military file down the edge of an overgrown field.
When he was ready, I pumped a short briefing file down the phone line.
First we had a 'foolproof' way of getting the Tangerine file down from Mermaid.
At that distance, the stone looked black and fatal, and it seemed to hang over the file down which he and Atiaran would walk.
I grabbed up my handbag and shoved the file down in the outside pocket, then headed for the front door, heart still pounding.
He saw the man-tracker floating motionless above the mud ahead, put the file down and pulled the tracker's control set out from under the root where he had left it.
Conrad laid the file down and reversed it on the shiny wood and opened it up, like he was displaying a rare treasure to interested connoisseurs.
She threw the file down and slammed the car into gear, burning rubber on the slick pavement as she sped out of the gas station.
And, gesturing to the guards, he threw the file down to the side and turned his head away, as if he had other business to attend to.