working student; student who works to pay for school
Refers to a student who works part-time or does side jobs to support themselves through school. Somewhat formal or literary; in everyday speech アルバイト学生 or 苦学生 are more common.
He works at a restaurant at night as a working student.
学僕 originally denoted a student who performed menial work, often at a school, to support or finance his studies; 僕 retains its older sense “servant.”