Rational article about family (8)
I believe the answer is:
thinking
'rational' is the definition.
('thinking' can be a synonym of 'rational')
'article about family' is the wordplay.
'article' becomes 'thing' (I've seen this before).
'about' means one lot of letters goes inside another.
'family' becomes 'kin' ('kin' can be a synonym of 'family').
'thing' enclosing 'kin' is 'THINKING'.
(Other definitions for thinking that I've seen before include "Thought" , "Take" , "Cogitating" , "rationale" , "Pondering" .)