Ferguson enjoyed a successful loan spell last season at St Andrews.
Clark told the Chronicle: "Fergie came in for us last season and was brilliant. He was great at left wing and left-back, he made goals and scored goals.
"He's a big part of what I am trying to do. I'm trying to turn the club around.
"With the financial situation, the young players I've got are important. I gave six Academy players their debuts this season."