We claim the ornamental design for an iron golf club head, as shown and described.
FIG. 1 is a top, rear perspective view of an iron golf club head of the present design;
FIG. 2 is a bottom, rear perspective view of the iron golf club head of FIG. 1; and,
FIG. 3 is a rear view of the iron golf club head of FIG. 1.
The ornamental design that is claimed is shown in solid lines in the drawings. The broken (dashed) lines shown in FIGS. 1 through 3 are included only for the purpose of illustrating environmental elements and break lines, and form no part of the claimed design.