The vastly experienced former Senegalese international is set to formally sign for Blues on a one-month contract once his visa application has been completed.
Having helped West Ham to promotion last season, free agent Diop has spent the last few weeks training with Blues at Wast Hills and Clark has been impressed with what he has seen of the 34-year-old.
Of course he is no stranger to Diop having spent a season playing with him with Fulham from 2004-5.
"I know him well and I had a good spell with him at Fulham when I played alongside him," said Clark. "He’s a very strong, physical type of player who is comfortable on the ball as well and we believe he can give us something a little bit different in that midfield area.
"He’s an impressive and imposing type of guy and a big central midfield player.
"He’s got a good pedigree and was part of the West Ham team that got promoted last year, so we’re looking for his experience and know-how and determination to help us through."
Clark said that he had no qualms about Diop's ongoing desire to football or his fitness, adding: "He's still got the keenness for the game. He’s been very impressive in training and been up for it and enthusiastic so we’re hoping that can continue."