Offender dismissed by decree (6)
I believe the answer is:
outlaw
'offender' is the definition.
(outlaw is a kind of offender)
'dismissed by decree' is the wordplay.
'dismissed' becomes 'out' (dismissed in cricket).
'by' means one lot of letters go next to another.
'decree' becomes 'law' (I've seen this in another clue).
'out'+'law'='OUTLAW'
(Other definitions for outlaw that I've seen before include "eg Robin Hood" , "Ban; fugitive" , "Ban, prohibit by legislation" , "Ban - bandit" , "Declare illegal" .)