One affected by this may often be accused of taking offence (11)
I believe the answer is:
kleptomania
'affected by this may often be accused of taking offence' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'one' is the wordplay.
I cannot really see how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for kleptomania that I've seen before include "Compulsion to steal" , "Stealing urge" , "urge to help oneself" , "Recurrent urge to steal" , "Impulse to steal" .)