Applesnails usuall get attacked by most types of fish to be honest. Why exactly would you be wanting the snails anyway just to look cool in your tank or ?
I've got mine in a seperate tank and they look fabulous their antenae are stretched out to full all the time - when they were in with the platies they sort of skulked around with only a small amount of 'foot' showing. When they get bitten they'll snap back into their shell (have a trapdoor) Once my pleco got caught in it
it was awful (he survived thankfully) but thats another story....
Applesnails I think are very useful in fry tanks as they are too slow to get the fry but they eat all the waste on the bottom of the tank keeping it nice and clean watchout cause they will come up to suck up all the fish food floating on the top of the tank (curl their foot into a circle and suck using their mouth the water in bringing the food closer
I haven't really answered your question yet though... a lot of people have the idea applesnail algae eater but in truth all they eat is that brown algae which most fish eat anyway, secondly be careful which snails you get some eat plants (ask for P. Bridgesi (golden ones are all p.bridgesi and are a safe bet)
Checkout
http/www.applesnail.net its a very useful/good resource and site.
Still haven't answered it well... I've never tried with clowns my fish and my snails were able to live together although my snails didn't live to their max they didn't show off many of the things I see now with them! They are resourceful critters though and so probably would survive any clown attack just be a bit reclusive
The choice is up to you really, if I was you... and you wanted applesnails either have them in a fry tank where they'll eat dead fry/wasted food or have them in a small tank of their own - 5-10 gallons is fine
Hope that somewhat helps B) B) Applesnails are cool. B)