The ornamental design for a spout for fuel, as shown and described.
FIG. 1 is a right side view of a spout for fuel, showing my new design in a state of use;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing of a nozzle in FIG. 1 is included for the purpose of illustrating environment of the article and forms no part of the claimed design.