The ornamental design for a drainagedevice for a vehicle, as shown and described.
FIG. 1 is a perspective view of the drainage device for a vehicle showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a right side elevation view thereof, to which the left side elevation view is a mirror image;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The drainage device for a vehicle is shown with a symbolic break in its length. The appearance of any portion of the drainage device for a vehicle between the breaks do not form part of the claimed design.