Some underwear revealing outlines (6)
I believe the answer is:
briefs
This clue is a double definition.
'some underwear' is the first definition.
(I've seen this in another clue)
'outlines' is the second definition.
(brief is a kind of outline)
'revealing' is the link.
(Other definitions for briefs that I've seen before include "Close-fitting underpants" , "Sets of instructions for lawyers" , "Pants" , "They are prepared for barristers' perusal" , "Digests" .)