Clevert received a Bachelor of Arts degree from Davis and Elkins College in 1969 and a Juris Doctor from Georgetown University Law Center in 1972.
He was an assistant district attorney of Milwaukee County, Wisconsin from 1972 to 1975.
He was an Assistant United States Attorney of the Eastern District of Wisconsin from 1975 to 1977, and was a Special Assistant United States Attorney for the Northern District of Illinois in 1977.
Clevert was a United States Bankruptcy Judge for the Eastern District of Wisconsin from 1977 to 1995, and was the Chief United States Bankruptcy Judge from 1986 to 1995.
On December 7, 1995, Clevert was nominated by President Bill Clinton to a seat on the United States District Court for the Eastern District of Wisconsin vacated by Terence T. Evans.