Family (and the rest) must adopt current type of energy (7)
I believe the answer is:
kinetic
'type of energy' is the definition.
'family and the rest must adopt current' is the wordplay.
'family' becomes 'kin' ('kin' can be a synonym of 'family').
'and the rest' becomes 'etc' (et cetera).
'must adopt' is an insertion indicator.
'current' becomes 'i' (symbol for electric current).
'etc' going around 'i' is 'etic'.
'kin'+'etic'='KINETIC'
(Other definitions for kinetic that I've seen before include "Relating to motion" , "Like a mobile" , "due to motion" , "Concerned with moving" , "Nick tie (anag.)" .)