Cover provided by second family (4)
I believe the answer is:
'cover' is the definition.
(I know that skin is a type of body covering)
'by second family' is the wordplay.
'by' means one lot of letters go next to another.
'second' becomes 's' (common abbreviation).
'family' becomes 'kin' (synonyms).
's' put next to 'kin' is 'SKIN'.
'provided' acts as a link.
(Other definitions for skin that I've seen before include "Remove the outer layer" , "Dermis" , "Fell" , "Surface layer" , "Scrape, as the knee" .)