Way off base (6)
(Other definitions for errant that I've seen before include "Offending" , "Travelling about or going astray" , "so some knights are called" , "Straying from the right course" , "Roving" .)
'way off base?' 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 "unaccounted for" , "Army offence of being missing from duty, briefly" , "Absent without permission, in short" , "'Absent without permission, initially (4)'" , "Of soldier, illegally absent - initially" .)