Well its going to depend on what his severance contract says.Surely if Clarko coaches next year he still keeps his entire payout from Hawthorn + whatever the new club pays him.
Why would Hawthorn get any discount to their softcap, given they have spent the money to pay him out?
If it says that "should he coach elsewhere and earn equivalent to or more then what Hawthorn are paying him, no payment will be made", my guess is that Hawthorn wouldn't have to pay him.