plug away peg away slog keep one's nose to the grindstone keep one's shoulder to the wheel
plug_away%2:41:00:: peg_away%2:41:00:: slog%2:41:00:: keep_one's_nose_to_the_grindstone%2:41:00:: keep_one's_shoulder_to_the_wheel%2:41:00::
work doggedly or persistently
She keeps plugging away at her dissertation