AFB truant (4)
I believe the answer is:
awol
'afb truant' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for awol that I've seen before include "'Absent without permission, initially (4)'" , "Absent without leave (abbr.)" , "On the lam" , "Not present when supposed to be" , "Absent without leave (abbrev.)" .)