At home, lust treated as offence (6)
I believe the answer is:
insult
'offence' is the definition.
(I know that insult is a type of offence)
'at home lust treated' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'treated' indicates an anagram.
'lust' is an anagram of 'sult'.
'in'+'sult'='INSULT'
'as' is the link.
(Other definitions for insult that I've seen before include "Abusive remark" , "Speak or act inm abusive way" , "Speak to or treat with disrespect" , "Hurtful and offensive remark" , "Speak rudely or offensively about" .)