sometimes kickers are just kickers but I find that the more you work with them, the better that they get. Does he just kick when you try to clip and or comb him or does he kick at other times as well? We have tried using a broom or something similar and just start messing with the legs to get them used to it.
My son's steer this year was a kicker He would kick with such force anytime anyone went near him. We would tie him and take a broom and touch him all over with it, and not stop even when he kicked. We would hold the end of the broom handle and rest the broom part on his hip and let him kick him until he was too tired to kick anymore. We also srayed his legs with water. It didnt' take but two to three sessions of this, and he quit. No more kick in him and he is a real sweetheart now! Good luck, be careful and be patient!
We had one that wanted to kick a little. We just tied her up on the washrack and sprayed water on her legs. She'd kick at the water and of course, hit nothing but we could keep spraying. She quit after a couple sessions.
However, we had a serious kicker several years ago that would kick hard & with deadly aim. Nothing stopped her. We turned her out because she was too dangerous to have around in a show type situation.
I have heard some people taking long streamers and put them on a fan. Then put behind them so the streamers blow on them. They should eventually stop kicking. I usually just wash and blow on them alot and they usually stop after a couple times. Luckily I have not had any kickers for quite a few years.