You will hear many things that people do to get their fish to host.
Tape a photo of a clown hosting to the glass so they can see it. I don't think it is something they learn, it is instinctive. Try if you like, it can't hurt but I don't think it will make your clown host, it got my maroon very angry.
When you feed, place food near the anemone, may make them notice it.
Keep in mind that it is not their natural host so it will take them time to build up resistance to it's sting. There is no gurantee they will host at all but at any rate it will take time. It took my ocellaris pair year to finally hoat my bta and my perc about a month. I wish there was a trick but there isn't really just have to let nature take it's course.