Hide small family (4)
I believe the answer is:
skin
'hide' is the definition.
(a hide is an animal skin)
'small family' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'family' becomes 'kin' (synonyms).
's'+'kin'='SKIN'
(Other definitions for skin that I've seen before include "External membrane of body" , "Pelt" , "Outer layer of tissue" , "Thin outer layer" , "Epidermis - peel" .)