[1] He was the son of Alexis Simon Belle, a well-known portrait painter and a Member of the Royal Academy of Painting and Sculpture in Paris and his wife, the painter and engraver Marie-Nicole Horthemels.
Clément too showed a talent for art and was taught by his mother.
In 1745 he went to Italy, where he spent 10 years studying the old masters and on his return to Paris was accepted into the Academy.
In 1755 he was appointed head of the art section at the Gobelins Manufactory, an historic tapestry producer in Paris.
At some point between 1791 and 1793, the three painters (Belle, Pierre Peyron and Joseph-Laurent Malaine) who worked at the Gobelins were dismissed.