Offend good, and confess (4)
I believe the answer is:
sing
'confess' is the definition.
(I've seen this before)
'offend good' is the wordplay.
'offend' becomes 'sin' (I am not sure about this - if you are sure you should believe this answer much more).
'good' becomes 'g' (abbreviation).
'sin'+'g'='SING'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for sing that I've seen before include "Make melodious sounds with voice" , "serenade" , "Confess" , "Celebrate" , "Turn informer" .)