Macheda grabbed a goal in each half, making it three goals in two games for City since signing on loan at the end of January.
Blues boss Clark explained: "I lost five players on loan on New Year's Day and had to rebuild the squad.
"It took a while and we lost three league games which knocked the stuffing out of us.
"Luckily I was able to recruit new players and they have done very well for us.
"We have got a bit of a conveyor belt from Manchester United, and we thank David Moyes for helping us.
"I only hope they don't do so well and they go then go back early."
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