If you took a year out for personal reasons or because your decision to look for a PhD was taken a couple of months after you graduated then it's no big deal. If you're asked, explain it, don't make too many excuses or blame other people. On your application mention the things you did do, don't spend time explaining why you were doing nothing. If you really have done nothing and for no good reason, then start doing something. Try and get some lab or other research experience by contacting people at relevant local institutions (universities, libraries, hospitals, museums, R&D companies) and volunteering to work for free.