Clark was his reserve team manager at Newcastle United, when Edgar was starting out in professional football.
"I coached Dave when he was a young player at Newcastle and I was the reserve manager," said the Blues boss. “He’s a good professional with a strong character and has leadership qualities.
"He actually started out as a right-sided centre-half, but broke into the Newcastle first-team as a right-back and played the majority of his games there as a right-back and actually scored his first goal as a right-back against Manchester United, which I remember well.
"He then decided it was time to move on and he went to Burnley and he’s played a lot of his games – certainly last season as a defensive central midfield player. His versatility is important to us in the way that we want to work. He can play in all those three positions.
"I know his character well and what he can bring to the group and to the team. I think we’ve done really well to get him because he played a huge part in what Burnley did last year (in getting promoted to the Barclays Premier League). When I spoke to Sean Dyche (the Burnley manager) he was really fulsome in his praise of what Dave had done."
Clark feels that Edgar will give his side extra physical presence, whichever position he plays.
"He’s competitive in the air and aggressive," added Clark. "Obviously he’s a lot more experienced and mature than when I first worked with him.
"David sees himself more as a central midfield player. But as I said, he plays all three positions equally as well and none of them are alien to him and he’s comfortable in all of them and that versatility is good for us."