In town, keep out of the centre of crime or sin (4)
I believe the answer is:
bari
'sin' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'in town keep out of the centre of crime' is the wordplay.
'in town keep' becomes 'bai' (I can't justify this - if you can you should give a lot more credence to this answer).
'out of' indicates putting letters inside (some letters on the outside of others).
'the centre of' indicates the central letters.
'crime' becomes 'porno' (porno is a kind of crime).
The middle of 'porno' is 'r'.
'bai' placed around 'r' is 'BARI'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for bari that I've seen before include "Adriatic resort" , "Adriatic seaport" , "Adriatic port" .)