To some extent, relatives manage fine (4,2)
I believe the answer is:
kind of
'to some extent' is the definition.
(thesaurus)
'relatives manage fine' is the wordplay.
'relatives' becomes 'kin' (I've seen this before).
'manage' becomes 'do' ('do' can be a synonym of 'manage').
'fine' becomes 'f' (abbreviation).
'kin'+'do'+'f'='KIND OF'
(Other definitions for kind of that I've seen before include "Rather" , "After a fashion" , "Not exactly" , "Somewhat" .)