The ornamental design for a hood for a garment, as shown and described.
FIG. 1 is a rear view of a hood for a garment where hair extends through a zippered opening.
FIG. 2 is a rear view of the hood for a garment where the zippered opening is closed.
FIG. 3 is a front view of the hood for a garment; and,
FIG. 4 is a side view of the hood for a garment.
The partial human figure and portions of the jacket outlined by broken lines assist to illustrate the environment of the hood for a garment and form no part of the claimed design.