Flay initially sweet family (4)
I believe the answer is:
skin
'flay' is the definition.
(I know that flay is a more specific form of the action skin)
'initially sweet family' is the wordplay.
'initially' indicates taking the first letters.
'family' becomes 'kin' (synonyms).
The first letter of 'sweet' is 's'.
's'+'kin'='SKIN'
(Other definitions for skin that I've seen before include "External membrane of body" , "Flense" , "Scrape, as the knee" , "Outer layer of, eg, apple" , "Pelt" .)