The ornamental design for a sucker for a conduitdredge, as shown and described.
FIG. 1 is a perspective view of a sucker for a conduit dredge, showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is another perspective view thereof; and,
FIG. 9 is another perspective view showing the sucker for conduit dredge in a position of use; wherein the broken lines shown depict environment only and form no part of the claim.