The ornamental design for a clip-in nostril expander, as shown and described.
FIG. 1 is a side elevation perspective view taken from the top and right side and above a clip-in nostril expander showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a right side elevation view thereof, it being understood that a left side view is a mirror image thereof;
FIG. 4 is a bottom plan view thereof:
FIG. 5 is a right end view thereof, it being understood that a left end view is a mirror image thereof; and,
FIG. 6 is a view like that of FIG. 1 that shows the clip-in nostril expander in dark lines that has been bent across a center strap that connects on its ends to left and right cylinders that are fitted into a person's nostrils that are shown in light lines, illustrating a use of the new design.