Crossword Genius

Answer about an offence (6)

Ross

I believe the answer is:

retort

Here is my best explanation:

'answer' is the definition.
(retorting is a kind of answering)

'about an offence' is the wordplay.
'about' becomes 're' (common abbreviation for 'with reference to').
'an offence' becomes 'tort' (legal term for a type of offence).
're'+'tort'='RETORT'