Offer food items that are about the size of their eyeball. In the wild, their stomach contents have shown they prefer to fill up with a bunch of smaller items verses fewer larger items. The larger a single food item is, the longer it takes to digest it, and these fish have been found with food rotting in their bellies.
Your best bet is to keep him full so the clown isn't as tantalizing, but a full grown fuzzy can take down a full size perc. A wiggling, live food item will be too much to resist at some point. Are you super attached to the clown? That sounds cold, but I personally take bigger risks with..... ummmmm.... the replaceables O.O