Hamilton’s first Ferrari win in Barcelona closed the gap to 41 points behind Mercedes’ championship leader Kimi Antonelli.
Clark is bidding to become the first wire-to-wire US Open winner since Martin Kaymer in 2014.
The wing chose to risk a refracture in order to play in Saturday’s showpiece, which ended in a 26-17 defeat by Northampton.
Stokes and Gus Atkinson are to return after being left out of the second Test against New Zealand for breaking a team curfew.
Dirt champion will head back to America ready to defend Breeders’ Cup crown.