The ornamental design for a fork for a forklift, as shown and described.
FIG. 1 is a front side perspective view of a fork for a forklift, showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is right side view thereof; and,
FIG. 7 is a left side view thereof.
The dash-dot broken line shown in the figures is included to define the bounds of the claimed design and form no part thereof. The evenly spaced broken lines are included to illustrate portions of the fork for a forklift and form no part of the claimed design.