embodiments of the present invention may include a clip mounting seat having a clip attachment surface , a peripheral wall and an opening . the peripheral wall extends from the clip attachment surface . the opening opens a part of an outer peripheral edge of the clip attachment surface . the clip attachment surface has an attachment hole , a guide groove and a tongue . the guide groove guides an insertion of a neck portion of the clip from the opening into the attachment hole . the tongue protrudes from an edge of the guide groove towards the attachment hole . the tongue is deflected to permit the neck portion to enter from the opening into the attachment hole . when the neck portion moves from the attachment hole toward the opening , the tongue is deflected by the neck portion in a closing direction .