The ornamental design for an alignmentattachment for a golf putter, as shown and described.
FIG. 1 is a top plan view of an alignment attachment for a golf putter
showing my new design, with the putter head shown in phantom for
illustrative purposes only;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a side elevational view, with the opposite side being a mirror
image thereof; and