Complex sentence: Robert Newton Calvert (9 March 1945, Pretoria, South Africa-14 August 1988) was the lead singer, poet and frontman of Hawkwind intermittently from 1972-1979, who went on to a less successful but intriguing separate career.
Split into simpler sentences: Robert Newton Calvert (9 March 1945, Pretoria, South Africa-14 August 1988) was a writer, poet and performer. He went on to a less successful but intriguing separate career.