Yes you can place live clams in the freezer and the live clams will survive in the freezer for up to 3 months or you can even just keep the live clams in the refrigerator which is usually good enough.
When freezing live clams you should place the live clams in moisture-vapor resistant bags.
Also be sure to press out any excess air from the bags before placing the bags with the live clams in the freezer.
Also always wait until you're ready to cook and eat the live clams before killing them because dead clams will start to grow bacteria on them which can make you sick.
So kill the live clam right before you plan to cook the live clam and you'll be okay.