Conceal skin (4)
I believe the answer is:
hide
I believe this clue is a double definition.
'conceal' is the first definition.
(I know that conceal can be written as hide)
'skin' is the second definition.
(I know that skin can be written as hide)
(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" .)