The Italian has been out of work since leaving Chelsea on New Year’s Day.
Clark called last year’s incident at Oakmont the “lowest point” of his career.
Itoje has completed more Test minutes than any other player in the game over the last decade.
The Sussex all-rounder is a left-arm spinner who has been batting in the top three for his county in Vitality Blast.
Newmarket and Nottingham on Thursday will now start in the morning.