Offender is not in court by order (6)
I believe the answer is:
outlaw
'offender' is the definition.
(outlaw is a kind of offender)
'not in court by order' is the wordplay.
'not in court' becomes 'out' (I can't justify this - if you can you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'order' becomes 'law'.
'out'+'law'='OUTLAW'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for outlaw that I've seen before include "Declare illegal" , "Robin Hood, for one" , "eg Robin Hood" , "Nonconformist" , "bar" .)