Hide individual's marks and conceal what one has done (5,4,6)

'and conceal what one has done' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'hide individual's' is the wordplay.
I cannot quite see how this works, but
'hide' could be 'cover' (covering is a kind of hiding) and 'cover' is found within the answer.
'individual's' could be 'ones' (an individual is one person) and 'ones' is located in the answer.
The remaining letters 'tracks' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'marks' is the link.

Can you help me to learn more?