I've seen a guy twice and he does not deserve to be blacklistsed. I checked him in advance and he was blacklisted. How does a guy clear his name on sites like this?

If he is blacklisted that means that the girl who did it probably thought he deserved it. Just because you guys get along great doesn't mean every other provider will. I had a friend who seen the same guy over and over and one day at the end of their date he grabbed her purse and took the money back and punched her in  then jaw. She got away from stabbing him in the leg with her knife, so you never know.

a follow up post to say if he has improved, made things right etc. Just because you had a nice time with a guy does not mean he did not deserve a blacklist from another woman. I've had guys treat me like gold then go rip off a provider down the road. Now, if this blacklist was for a bad review (and, they often are) that is simply fked up and he should contact all boards she is on, to report her.

Otherwise, all you can do is give him a good reference and/or whitelist him. As the others have said, just because he was good with you doesn't mean he was good with all providers. (Also as London said, some are blacklisted for stupid reasons).
If you give hom good references, whitelisting, etc., then that can counter the blacklist and it is up to future ladies if they want to see him.