jager67, I would try to pick the anemone off the clam. It certainly will sting the clams delicate mantle if they touch. A burned mantle will stress a clam to death. I would try to use a pair of tweezers or something that you can get the anemone off with. Taking the clam out of the tank for a few minutes will not hurt it.
The only thing you will need to do in replacing the clam is to burp it, to release any air trapped inside the
clam shell. This is done by gently swishing the clam held on the end from side to side.