In Ansbach he worked for the Margrave Carl Wilhelm Friderich.
In Brühl he worked for Cologne’s Archbishop and German Empire Prince Elector Clemens August von Wittelsbach. Here he assisted Bavarian Court master builder, architect François de Cuvilliés 1734-1735 on the Elector’s hunting lodge Falkenlust (also known as Schloss Falkenlust), on the grounds of Augustusburg (also known as Schloss Augustusburg). These buildings are now considered the most important buildings of the late Baroque and Rococo in all of the Rhineland. They were declared a World Heritage Site in 1984 by UNESCO.
Figure groups in wall niches in the upper vestibule sculpted by le Clerc are still extant.
He was, along with Elias David Häusser and Nicolai Eigtved, one of the primary figures involved in the creation of Christiansborg. He was named head of the sculpture and stone work at the castle in 1737. Most of the work he did at Christiansborg, however, was eventually lost, having been destroyed in the fire of 1794.
Existing still to this day are wood carved vases in Christiansborg’s horse stalls, and relief medallions on the side of the Marble Bridge (Marmorbro) that leads to the castle’s main entrance. Four perspective drawings he made of Christiansborg 1746-1747 are in the collection of the Engraving Museum in Copenhagen.
Destroyed work from the castle includes the cornices, capitals and frames of the windows; carved wall panels, fireplaces and console tables in both the king’s and the queen’s suites; the golden dining room with buffet and chandelier; sculptures on the balustrade, and all sculpture work in the castle church.
In 1739 he created a fountain in the King’s Garden (Kongens Have) at Rosenborg Castle representing a boy with a swan.. The sandstone original was replaced by a bronze figure featuring a similar motif; the replacement was designed and produced by Hermann Ernst Freund in 1837.
Frederik V affirmed his support for the Academy by issuing a royal resolution on February 12, 1748. In addition to a financial commitment there were specified organizational changes. At the same time le Clerc was named professor to the Academy, one of the first artists to be so named.
Frederik V established the current Academy of Art (now called Det kongelige skildre-, billedhugger- og bygningsakademi, in English "The Royal Painting, Sculpture and Architecture Academy") in 1754. He was made a member of the Academy that same year, and also named professor. Le Clerc did not play a significant role in the new Academy, other than as a teacher. After Frederik V had summoned another French-born sculptor Jacques Saly to Denmark in 1752 to create a monumental equestrian statue of himself for the courtyard of Amalienborg Palace, le Clerc’s importance went down and his production became small.
He continued as professor at the Academy until his death. His artistic skills were not employed much in his later years. He died in Copenhagen, in his house on Brolæggerstræde, on March, 8, 1771. He was buried in the Reformed Cemetery ("Reformeret Kirkegård"), Copenhagen.
But even before the great fire destroyed so much of his work, the tides had shifted against him. Rococo, as an artistic ideal, had been discredited, and Frederik V, the successor king to le Clerc’s great patron, chose to favour other artists.
In addition, some drawing of his work are still in existence.
His portrait of Carl Gustaf Pilo is in the keepsake of the Academy.