Born in Kiagbodo, Nigeria, to an Ijaw father and Urhobo mother, Clark received his early education at the Native Authority School, Okrika (Ofinibenya-Ama), in Burutu LGA (then Western Ijaw) and the prestigious Government College in Ughelli, and his BA degree in English at the University of Ibadan, where he edited various magazines, including the "Beacon" and The "Horn". Upon graduation from Ibadan in 1960, he worked as an information officer in the Ministry of Information, in the old Western Region of Nigeria, as features editor of the "Daily Express", and as a research fellow at the Institute of African Studies, University of Ibadan. He served for several years as a professor of English at the University of Lagos, a position from which he retired in 1980. While at the University of Lagos he was co-editor of the literary magazine "Black Orpheus".