The ornamental design for a golfclubhead for a putter, as shown and described.
FIG. 1 is a top perspective view of a golf club head for a putter showing our new design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a left side 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 head are for environmental purposes only and form no part of the claimed design.