Buy-back clauses are all the rage these days. Even Manchester United, a club so often left behind by the trends of the modern game, got involved eventually. Hannibal Mejbri, should he join Sevilla on a permanent basis following his loan spell at the La Liga outfit – a prospect which admittedly looks very unlikely right now – could return to Manchester United for £28 million later down the line. The Red Devils sent Alvaro Fernandez to Benfica on a similar deal. Zidane Iqbal, meanwhile, has a buy-back clause in his own deal at FC Utrecht, just in case a midfielder sold on a pittance goes on to d…