He attended St Peter's De La Salle School in Surry Hills, leaving at the age of 14 to work in a boot pattern factory.
After studying Marxism with the intention of converting his socialist wife to Catholicism, he became a Marxist himself and joined the Communist Party of Australia in 1943.
[1] Clancy contested numerous elections for the Communist Party, and was on the central committee executive during the 1968 split after the Soviet Union's invasion of Czechoslovakia.
[1] Clancy's interest in classical music saw him serve from 1973 to 1978 as the trade union representative on the board of the Australian Opera, and he was a passionate supporter of the South Sydney Rabbitohs.
He was awarded the Order of People's Friendship by the Soviet Union in 1979 and was included on the New South Wales Labor Council's list of leading unionists in 1980.