He was the father of the British sociologist Simon Clarke and was the brother-in-law of screenwriter Philip Mackie.
He left school to become an apprentice electrician, but began working in the theatre, and was briefly an actor.
He served in the Royal Artillery during World War II, and subsequently studied to become a barrister.
On return to the UK, Clarke worked mainly as a television writer, creating plays, drama series and sitcoms.
In 1958 he became part of the "Drama Experimental Unit" at the BBC, along with others such as Troy Kennedy Martin and Anthony Pelissier; they were disbanded in 1960.