CuCl2+F2—>CuF2+Cl2.
This is a single replacement because there is one compound and one element. Picture Cu as ‘A’ Cl2 as ‘B’ and F2 as ‘C.’ So AB+C—>AC+B. A and B “broke up” and that resulted to A going with C to create the compound CuF2 leaving Cl2 alone.