The ornamental design for a closure, as shown and described.
FIG. 1 is a front, top, right perspective view of a closure showing our new design;
FIG. 2 is a front, bottom, left perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines of even length shown in the drawings illustrate portions of the closure that form no part of the claimed design. The broken lines of uneven length depict the boundary of the claimed design.