A grommet for installation in an opening of a panel comprises an elastically deformable material having a longitudinal axis extending from a proximal end to a distal end of a grommet body. The grommet body comprises an aperture extending longitudinally through the grommet body between the proximal end and the distal end. A wall-engaging segment defines a longitudinal segment of the aperture and is located to be enclosed by a wall of the opening when the grommet is installed in the panel. A clamping element occludes the aperture in the wall-engaging segment and comprises at least one longitudinally extending through-hole sized and configured to receive an elongated element. The clamping element is located to apply a compressive force on the elongated element to retain the elongated element in the through-hole of the grommet body responsive to disposition of the wall-engaging segment in the opening of the panel.