Clement started out as a self-taught amateur mechanic going on to become a highly skilled engineer, manufacturing special purpose machinery. Works manager and chief draughtsman for Bramah in 1813, then for Maudslay in 1815, Clement set up on his own in Newington, London in 1817 making lathes and planing machines. During the 1820s he made fluted taps and dies and standardised screw threads, on a small scale.

Clement is remembered as the maker of Charles Babbage's first Difference Engine, under construction between 1824 and 1833. This was the earliest known automatic calculator and one of the finest examples of precision engineering of its day.