Free to get new skin (4)
I believe the answer is:
rind
'skin' is the definition.
('rind' can be a synonym of 'skin')
'free to get new' is the wordplay.
'free' becomes 'rid' ('rid' can be a synonym of 'free'**).
'to get' means one lot of letters goes inside another.
'new' becomes 'n'.
'rid' going around 'n' is 'RIND'.
(Other definitions for rind that I've seen before include "Outer layer (of cheese)" , "Hard outer skin, of an orange say" , "tough skin" , "Outer edge of a bacon rasher" , "Outer skin of citrus fruit" .)