Pure set about the man getting a fresh start (5,5)

I believe the answer is:

clean sheet

I'm a little stuck... Click here to teach me more about this clue!

'the man getting a fresh start' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'pure set' is the wordplay.
'pure' becomes 'clean' (associated in meaning).
'set' becomes 'sheet' (I can't explain this - if you can you should give a lot more credence to this answer).
'clean'+'sheet'='CLEAN SHEET'

'about' acts as a link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

Want a hint initially instead of a full solution? Install my app