Clements made his first professional appearance on the stage in 1930, then worked with Nigel Playfair and afterwards spent a few years in Ben Greet's Shakespearean Company.

[1] Clements married the actress Kay Hammond and together they had a critical success with their West End revival of Noël Coward's play Private Lives in 1945.

[3] In 1952 they both appeared in Clements's own play The Happy Marriage, an adaptation of Jean Bernard-Luc's Le Complexe de Philemon [fr].

[5] In December 1951 Clements directed Man and Superman in the West End, and played the role of John Tanner alongside Allan Cuthbertson.

He made quite an impression opposite Robert Donat and Marlene Dietrich in Knight Without Armour as Poushkoff, a sensitive, conflicted young commissar who saves their lives during the Russian Revolution.