Welcome to my life with my clowns LOl.. I have a 13 year old pair of ocellaris that have killed every nem,hammer,frog,torch that has hosted them forever. They get so aggressive when breeding that either the nem will take a hike or the euphyllia(spelling) will just die.
I now know that I can't have anything with swaying tentacles in the tank. That have there little stub of a branching hammer (once colony like 10" across) three little branches, That they beat up on a daily basis and little do they know that's the last one they will get LOL..
I think if your specimen is big enough you should be fine as long as your clown is not like mine and constantly attack the base of the nem cause they want to lay the eggs on that one spot.. I swear I think my pair is a little touched in the smart department as they also used to steal all food I gave the nem.. Most other clowns will feed the host mine seem like they try there hardest to steal from it. Most times they wouldn't even eat it lol just spit it out..
Sorry rant over ha ha.