Celtic's radar for a summer switch according to reports in Italy.A defensive recruitment drive is on the horizon at Parkhead this summer with Kristoffer Ajer likely to attract interest and Shane Duffy likely to leave Glasgow and bring the curtain down on an ill-fated loan from Brighton.Christopher Jullien will be expected to be back from injury, however, but after a poor record at the back this term Nick Hammond will likely be looking to add new faces.Italian outlet Tuttohellasverona report that