Check your stratagem cards, there is a card you can play against your, sticky, fingered, leaders to try and recoup the funds they have stolen. It's not that rare of a card, I frequently get them in all my games.
Do you mean the 'Ear Lock' card? Yeah i just got that last night, however cannot recover any stolen funds but at least it will reduce corruption every turn by 5 points (not sure how long this lasts?) there is another investigate leader stratagem too, which i think will recover some of the stolen money but you need a decent roll modifier to pull it off.
But I am wondering when you don't have Ear lock or unable to succeed in the Investigate Leader Stratagem can demoting them to the reserve pool stop them stealing more money? this one advisor took 900cr, although that figure might be the total over the 60 turns?
Nope not the "Ear Lock" this one is called "Investigate Leader" - "Try to recoup as much stolen credits from a corrupt leader as possible" "Difficulty to Investigate is 80 + Authority of target". I don't know if demoting them to the reserve pool stops the corruption, my guess is that it should stop since he/she no longer has access to the "Widows and Orphans cash-box locked away in the office holders desk.