Cartoonist's invoice pretty steep (4,4)

'cartoonist's' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'invoice pretty steep' is the wordplay.
I cannot really see how this works, but
'invoice' could be 'bill' ('bill' can be a synonym of 'invoice') and 'bill' is found within the answer.
The remaining letters 'tidy' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?