The ornamental design for a lid for a container, as shown and described.
FIG. 1 is a first perspective top view of a lid for a container showing our new design, the lid being in a closed state and shown above a top container of an exploded stack of cooperating containers,
FIGS. 2, 3 and 4 are second, third and fourth perspective top views thereof shown above a single cooperating container,
FIGS. 5 and 6 are fifth and sixth perspective top views thereof when its access flap is partly opened,
FIG. 7 is a seventh perspective top view thereof when the access flap is fully opened,
FIG. 8 is a side view of FIG. 7,
FIG. 9 is a bottom perspective bottom view thereof with the access flap partly opened; and,
FIG. 10 is a perspective bottom view thereof in a closed state.
The broken line showing of containers is included for the purpose of illustrating environment and forms no part of the claimed design.