Sunderland have less than three weeks to keep a tight grip on Jack Clarke. The winger was expected to leave Sunderland for the Premier League this summer, but is yet to receive any bids due to his £25 million price tag. It was business as normal for Clarke at the weekend, as he continued his role in the starting line-up and got off the mark when he doubled the lead against Cardiff City. Interest is very likely to heat up in the final weeks of the window, but fans will be praying that the club can keep hold of him for another season. Clarke’s valuation will drop next summer if he is to stay, wi…