Clarke,who made twelve appearances for City last season, collapsed at half-time of the game and had to be rescusitated by paramedics using a defribilator whilst Martin Allen was led a team talk on the side of the pitch.
Both sets of players plus the referee agreed that they were in no state to carry on and the game was abandoned.
Clarke was rushed to the Queens Medical Centre in Nottingham and is conscious with his condition being given as "stable".
All at Covsupport wish Clarkey a full recovery.
In the League Cup, Craig Bellamy scored his first goal for West Ham in a 2-1 win at Bristol Rovers. The shocks saw Morecambe win 3-1 at Wolves, Blackpool beating Derby on pens,Hull winning at Wigan and Luton beating Sunderland with Paul Furlong scoring twice.
Gary McSheffrey scored the winner for Birmingham v Hull and Dion Dublin scored for Norwich in a penalties win at Rochdale.