The state of being an employee; employment.
To hire (somebody for work or a job).
To use (somebody for a job, or something for a task).
To make busy.
Work.
By extension, analogous to boffin, nerd, smart aleck. Often pejorative.
One who swots.
Vigorous study at an educational institution.
To study with effort or determination (object of study indicated by "up on").