School absentee (6)
I believe the answer is:
truant
'school absentee' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for truant that I've seen before include "Straying" , "One is absent from school without permission" , "Runaway" , "Pupil skipping school" , "Pupil staying away from school" .)