In town, keep out of the centre of crime or sin (4)

'sin' is the definition.
Both the definition and answer are singular nouns.
Maybe there's an association between them I don't understand?

'in town keep out of the centre of crime' is the wordplay.
'in town keep' becomes 'bai' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'out of' means one lot of letters goes inside another (some letters on the outside of others).
'the centre of' says to take the centre.
'crime' becomes 'porno' (porno is a kind of crime).
The middle letter of 'porno' is 'r'.
'bai' placed around 'r' is 'BARI'.

'or' is the link.

Can you help me to learn more?