The ornamental design for a golfclubhead for a putter, as shown and described.
FIG. 1 is a perspective of a golf club head for a putter showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a toe end view thereof;
FIG. 5 is a heel view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom perspective view thereof.
The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The broken lines showing the remainder of the golf club are for environmental purposes only and form no part of the claimed design.