Unworried, makes up for it with no difficulty (2,4,4)

'unworried' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'makes up for it with no difficulty' is the wordplay.
'makes up for' becomes 'atones' (I've seen this in another clue).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'with no difficulty' becomes 'ase' (I can't justify this - if you can you should give a lot more credence to this answer).
'atones'+'e'+'ase'='AT ONES EASE'

Can you help me to learn more?