The ornamental design for a marker for surgicalinstrument, as shown and described.
FIG. 1 is a perspective view of a marker for surgical instrument showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken line showing in the drawings is included for the purpose of illustrating portions of the marker for surgical instrument and forms no part of the claimed design.