Thanks, Alvin (and Norah!)
5 . Abbreviation followed by an anagram (naff) - this is a piece (of cloth, say)
6 D. UN is United Nations, large body, Natural is another word, an old one, for the B*****d
12 The latest - gives the first word, the latest fashion say.
Party = the usual two-letters for an event+ 'Gratuitous leader' indicates using the first letter of a word. The answer is grub, as in food (not insect)