Simpson joins the League One club, whom City visit on July 25th in a deal around the £300k mark after making 28 starts and 43 sub appearances for City.
Speaking to Virgin Media, Clark said: "I'm absolutely thrilled to have Robbie Simpson moving to the club. He is a young, hungry player who wants to get better and that is exactly what I want.
"People who are looking at his recent goalscoring record need to realise that he has played 95% of his games out of position for Coventry.
"Robbie will give us a physical presence in attack; he works very hard and has a hammer of a right foot. I'm looking forward to working with him.