Completely naked (8)
'completely naked' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for starkers that I've seen before include "Like fairytale emperor" , "Not wearing a stitch" , "Completely naked" , "Wearing no clothes" , "exposed" .)
(Other definitions for au naturel that I've seen before include "Very simply" , "Naked in French, to aural tune" , "Cooked plainly or raw" , "Nancy's naked" , "served without dressing" .)