Philippe Clement will know that this summer’s transfer window is a crucial one at Rangers. With as many as six Rangers first-teamers out of contract in the coming months, and three loan players coming to the end of their short term deals, there are some big decisions to be made. With some high-earners in the team also still not contributing anywhere near enough, one suspects talk of a summer transfer overhaul is not just chatter. But one player who appears to be a genuine target for Rangers is RC Lens loanee Oscar Cortes, who joined the club on loan in January. However, a devastating injury, a…