As a seminarian at the Almo Collegio Capranica Clemente Micara studied at various universities of Rome Catholic theology and philosophy and received on 20 September 1902, the sacrament of Holy Orders. After further studies in 1904, he entered the diplomatic service of the Holy See a. Until 1909 he worked in the Vatican Secretariat of State, from 1909 to 1915 he was secretary of the Apostolic Nunciature in Argentina. After a brief stint in Belgium, he was 1916 staff of the Apostolic Nunciature in Austria. 1919 and 1920 he was a Papal envoy to Czechoslovakia.
On August 8, 1920 he received after the appointed Titular Archbishop of Apamea in Syria by Cardinal Pietro Gasparri consecrated bishop and was Apostolic Nuncio to Czechoslovakia. From 1923 he provided the same task in Belgium and was also Internuncio for the Grand Duchy of Luxembourg. During the German occupation in the years 1940 to 1944 Clemente Micara fled to Rome, before he could start work again in Brussels in 1944.
On February 18, 1946 it took Pope Pius XII. on a cardinal priest with the titular church of Santa Maria sopra Minerva in the College of Cardinals and raised him in the same year as Cardinal Bishop of Velletri. In 1950 he appointed him Prefect of the Congregation for Religious and for Pro- Prefect of the Congregation of Rites. From these offices he resigned in 1953.
Clemente Micara represented in the following years as papal legate to the Pope worldwide at numerous celebrations. In this capacity Micara was the German Catholics already become known in August 1948, when he represented the Pope at the celebrations of the Cologne Domfest, with which both the 700th anniversary of the start of Dombaus as well as the reopening of the cathedral after the devastation of World War II was celebrated. In 1951 he was Cardinal Vicar of Rome. He participated in the years 1962 to 1964 at the first session of the Second Vatican Council.
He died on 11 March 1965 in Rome and was buried in the Basilica of Santa Maria sopra Minerva.
- 1956: Grand Cross of Merit of the Federal Republic of Germany
- 1963: Grand Cross of the Order of Merit of the Italian Republic
- Member of the Order of Malta: Honour and Devotion Grand Cross - Bailli