I think Schar/Lejeune/Laecelles is our best combination at the back, but with Lejeune prone to getting crocked, and Laecelles erratic, there's definitely a place for Clark. Schar is our best defender by a clear distance though.
I'd go Schar, Lascelles, Clark with Fernandes/Lejeune backup. Fede's a good option - Lejeune I fear is just too slow.