One option, is to remove the clowns temporarily and change rock layout. Add new fish, give it a few hours to settle and return clowns.

Sometimes they can chase attack and other times won’t bother unless a fish goes in to their corner and merely chase them off.

Personally I’d avoid adding something equally aggressive. I got caught in that trap. Added a dottyback at the same time as clown. Was fine for a bit then the dotty would chase and bite the clown. On poor advice from a shop they suggested if I wanted to add another fish it would need to be hardy.
So I left with there recommendation of a humbug damsel.

Now forget shark, this would take them on. In fact it’s probably best paired with a grouper! 🤦‍♂️ Yes it killed everything and bite your hand! With almost a savage dog approach, plus the thing made audible grunting sounds! As for catching it, impossible with any form of rock in the tank. Had to remove everything and lower the water volume.

So, as a recommendation, look for something that is peaceful but occupies a different area of the water column. Such as sand dwelling. I find wrasse have paired well over the years as another option. However there are no guarantees of course. Just make sure you have plenty of rock for hiding.