Despise offence initially, then again (5)
I believe the answer is:
abhor
'despise' is the definition.
(abhor means to detest)
'offence initially then again' is the wordplay.
'offence initially' becomes 'abh' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'then again' becomes 'or' (both can mean 'alternatively').
'abh'+'or'='ABHOR'
Can you help me to learn more?
(Other definitions for abhor that I've seen before include "Find horrible" , "Can't bear" , "Regard with repugnance" , "Loathe, detest" , "Reject" .)