You could try running the clown in either pimafix or melafix, or possibly both at the same time. I'm not 100% sure on that but you'd have to check them out and follow their instructions.
PimaFix
Treats cotton-like fungal infections, and both internal and external bacterial infections. PimaFix harnesses the unique antifungal and antibacterial properties of the West Indian Bay Tree (Pimenta racemosa) for a safe and natural remedy; prevents the development of resistant strains of disease-causing organisms. Will not discolor water, affect biological filter, or pH during treatment. Will not harm aquatic plants. For extreme cases, PimaFix can safely be used with MelaFix to provide the added benefit of quick tissue regeneration and wound healing. 8 oz doses 400 gallons.
MelaFix
Contains the natural botanical extract from the Tea Tree (Melaleuca), an excellent alternative to resistant strains of bacteria that are unaffected by traditional medications. Treats bacterial infections such as red ulcers, fin and tail rot, cloudy eyes, mouth fungus, and others in as little as 4 days. Also heals open wounds, ulcers, and damaged fins. Doesn't affect pH; safe for invertebrates. NEW MelaFix Marine can also be used with corals to control bacterial infections, reverse coral degradation and remove parasitic flatworms. 8 oz MelaFix treats 480 gallons of marine or freshwater. 64 oz MelaFix is a concentrated formula and treats 19,000 gallons. 8 oz MelaFix Marine treats 474 gallons marine water.
From that it seems you can run them together. If you follow the directions you can run this in your reef tank without harm to corals or anemones. Just make sure you follow the water change schedule and keep your skimmer off for a bit.