Born in Cologne, Prussia, Clever attended the gymnasium of Cologne and the University of Bonn. Immigrated to the United States in 1848 and settled in Santa Fe, N.Mex., in 1850. He engaged in trade from 1855 to 1862. He was appointed United States marshal for New Mexico in 1857. He became one of the owners of the Santa Fe Weekly Gazette, a paper published in English and Spanish, in 1858. He studied law. He was admitted to the bar in 1861 and commenced practice in Santa Fe, N.Mex.. He was appointed United States marshal and census enumerator in 1861. He served as adjutant on the staff of General Canby at the Battle of Valverde. He served as adjutant general of New Mexico 1861-1865 and in 1867 and 1868. Attorney general 1862-1867. Presented credentials as a Democratic Delegate-elect to the Fortieth Congress and served from September 2, 1867 (date of election), to February 20, 1869, when he was succeeded by J. Francisco Chaves, who contested the election. He was appointed one of the incorporators of the Centennial Exposition in 1869. He served as a commissioner to revise and codify the laws of New Mexico. He engaged in the practice of law until his death in Tome, Valencia County, N.Mex., on July 8, 1874. He was interred in the National Cemetery, Santa Fe, N.Mex.