Elegant unicorn has a garment (5)
I believe the answer is:
tunic
'a garment' is the definition.
(historical type of garment)
'elegant unicorn has' is the wordplay.
'has' says the answer is hidden in the clue.
'TUNIC' is hidden in the letters of 'elegant unicorn'.
(Other definitions for tunic that I've seen before include "Roman garment" , "Schoolgirl's dress" , "Shift" , "Cut in (anag)" , "Short uniform coat" .)