Conceal skin (4)
I believe the answer is:
hide
I believe this clue is a double definition.
'conceal' is the first definition.
(synonyms)
'skin' is the second definition.
(hide is a kind of skin)
(Other definitions for hide that I've seen before include "Conceal - skin" , "Tanned skin of an animal" , "Not show" , "A flower; an instrument" , "Secrete, conceal" .)