The ornamental design for a holster for a drill, as shown and described.
FIG. 1 is a perspective view of a holster for a drill showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a front elevation view thereof with the belt loop extended;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a rear elevation view thereof with the belt loop extended;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a right side elevation view thereof;
FIG. 8 is a bottom plan view thereof; and,
FIG. 9 is a top plan view thereof.
The broken lines in FIGS. 3, 4, 5, 6, 7 and 9 outlining a clasp, illustrate portions of a holster for a drill that form no part of the claimed invention.