Is Bill Clinton Irish

No. He's an American of mostly English descent. His sole claim to being of Irish heritage is the fact that his mother, a third-generation American, had a typically Irish last name (Cassidy). However, there is no documentation proving Clinton's claim of being Irish-American like his hero Jack Kennedy.

Actually, a lot of Americans erroneously claim to be "Irish", when they're at most Irish-American, or more likely, simply an American of some Irish ethnicity.