The ornamental design of a bureau for an aircraft, as shown and described.
FIG. 1 is an upper perspective view of the bureau for an aircraft;
FIG. 2 is a front view of the bureau shown in FIG. 1;
FIG. 3 is a right-end view of the bureau shown in FIG. 1;
FIG. 4 is a left-end view of the bureau shown in FIG. 1; and,
FIG. 5 is a top view of the bureau shown in FIG. 1.
The bottom view and the rear view of the bureau form no part of the claimed subject matter and are therefore omitted. The broken lines shown in the figures represent portions of the bureau that form no part of the claimed design.