Pupil living at school (7)
I believe the answer is:
boarder
'pupil living at school' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for boarder that I've seen before include "Live-in school pupil" , "one that's getting on plane" , "Resident pupil" , "Schoolchild perhaps" , "School liver-in" .)