Newcastle United are worried they might have to sell one of their top stars this summer, and all the talk is about Bruno Guimaraes. While it has been claimed that he currently envisions remaining at St James’ Park beyond this summer, his £100million release clause continues to hang over his head. And it will loom even larger if the Magpies fail to qualify for Europe. Given the Premier League’s profit and sustainability rules, it has been theorised that selling Bruno Guimaraes is best for business. It would allow Newcastle United to reinvest in multiple players, although that comes with its own…