one thing that surprisingly works when trying to get a clown to host in an anemone, let the anemone get settled to the point that it plants its foot. wait for night time (or if you can get your tank in complete darkness.)
it must be completely dark, if you have moon lights on your hood, unplug them. you want it completely dark. wait 15 to 20 minutes. from there use a flashlight or the light from the cell phone and light up the anemone so it is the only thing with light. within 15 minutes the clown should go to the anemone and begin hosting with it. (that is if it will host). after it hosts keep it lit for another 5 minutes, then you can turn the lights back on as you please, they should continue to host it.
i had a tiny bubble tip anemone and i got my clown to host in it, even though the clown was slightly bigger then it by using this method. the clown paid it no mind for weeks. within minutes of doing this, it began hosting it