Clarke composed the incidental music for the Doctor Who serial The Sea Devils (1972); it was the second score that the Radiophonic Workshop provided for the series.
The score was experimental, unusual and controversial for Doctor Who at the time, with producer Barry Letts insisting that substantial edits be made for the finished programme.
His score for the serial has been described as "startling in its range of obtrusive electronic timbres and relative melodic paucity", "mixed music and sound effects" and "presented uncomfortable sounds to a substantial early evening audience on Saturdays in a way not duplicated in Britain before or since".
He continued to work on the series on a regular basis until 1986, composing the music for Enlightenment, Resurrection of the Daleks, The Twin Dilemma, Attack of the Cybermen and Terror of the Vervoids.
Clarke composed the 1976 radio piece August 2026: There Will Come Soft Rains, based on a short story by Ray Bradbury.