The 23-year-old originally joined the Minstermen from Hull City in May 2016, making his debut in the opening day 1-1 draw at Maidstone United.
However, Clappison has since been restricted to nine starts and a single substitute appearance - the most recent of those being in a 2-0 defeat at Southport in October of last year.
He was subsequently sent out on loan to Boston United for the remainder of the campaign, having had loan spells with Histon and FC Halifax Town whilst still on Hull`s books.