Terriers boss Clark said of Chadwick: "I know him from my time at Norwich and he's not a dirty player.
"Both of them went in hard and fair. Luke attempted to get the ball, but mistimed his challenge. I don't think he deserved a yellow card for that.
"Every season the game seems to get more difficult for referees. Rules come in that take out the physical aspect of football. I believe the game is a contact sport and accept that things like this are bound to happen."