Members of family regularly seen in pieces (7)
I believe the answer is:
parents
'members of family' is the definition.
(parents are part of one's family)
'regularly seen in pieces' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'in' means one lot of letters goes inside another.
'pieces' becomes 'parts' ('part' can be a synonym of 'piece').
The alternating letters of 'seen' are 'en'.
'en' going into 'parts' is 'PARENTS'.
(Other definitions for parents that I've seen before include "Mothers and fathers" , "Entraps (anag.)" , "Mum and dad" , "Mother and father" .)