The ornamental design for a lid for a container, as shown and described.
FIG. 1 is a magnified, fragmentary, front, top perspective view of a container showing our new design for a lid for a container;
FIG. 2 is a front, top perspective view thereof;
FIG. 3 is a top view thereof; and,
FIG. 4 is a right side view thereof, with the left side, front, and rear views appearing identical thereto.
The even-length broken lines represent claimed perforations on the lid for the container. The uneven-length broken lines showing the remainder of the lid and container are for environmental purposes only and form no part of the claimed design.