The midfielder was injured making a tackle in the 68th minute of City's 2-1 defeat on Tuesday night at Nottingham Forest.
It has since been announced that Clingan suffered a knee ligament injury on Tuesday night and he will be out for four to six weeks.
The injury has seen Clingan forced to withdraw from the Northern Ireland team to face Morocco next Wednesday. Clingan joins Maik Taylor, Chris Beard and Corry Evans who have withdrawn due to injury whilst Grant McCann is out as his Peterborough United side are involved in an FA Cup replay.
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