15A Of hair tied at the nape of the neck (2,5) - E?, Q?E?E I'm assuming this is EN QUEUE with queue meaning pigtail?
13A Dialectal interjection expressing failure to understand (4) - ?N?N I'm not sure whether this is HNNN in which case a poor clue I think, or it could be ANAN which occurs in Shakespeare roughly as "what did you say?"