He was raised in a strict Presbyterian family on the island of Raasay, immersed in Gaelic culture and literature from birth, but abandoned religion for socialism. In the late 1930s, he befriended many Scottish Renaissance figures, such as Hugh MacDiarmid and Douglas Young. He was wounded three times while serving in the Royal Corps of Signals during the North African Campaign. MacLean published little after the war, due to his perfectionism. In 1956, he became head teacher at Plockton High School, where he advocated for the use of the Gaelic language in formal education.