Renovateur wouldnt be possible to clean this!! If you have renomat use it (one-two really light passes) to remove old polish and open the pores of the leather! Then use distilled white vinegar (credits to Patrick booth on that) solution :
70ml water(preferably distilled )
1ml lemon (i found that this helps greasy stains be diluted a lot faster) !!
the other option is to use saddle soap but its quit harsh and then you have to use a lot different creams to restore ph and oils in the leather