Criminal not finished being involved in evil - that's a certainty (6)

'criminal not finished' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'involved in evil that's a certainty' is the wordplay.
'involved in' means one lot of letters goes inside another.
'evil' becomes 'sin' (synonyms).
'that's a certainty' becomes 'hoo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sin' going around 'hoo' is 'SHOOIN'.

'being' acts as a link.

Can you help me to learn more?