Clark was born in Rangiora, New Zealand on 16 February 1935, to parents Reginald Hawes Clark and Marjorie Alice Clark. He attended Marlborough College, Blenheim, and Christs College, Christchurch before pursuing bachelors and master's at Canterbury University College. Clark was a research and teaching fellow under William Fyfe at the University of Otago in 1958. From 1958 to 1961, Clark worked toward a doctorate advised by Ronald Sydney Nyholm and Jack Lewis at University College London and was awarded a PhD degree for his work on titanium complexes in 1961. The University of London later awarded Clark a DSc in 1969.