Strain from day supporting family (4)
I believe the answer is:
kind
'strain' is the definition.
(thesaurus)
'day supporting family' is the wordplay.
'day' becomes 'd' (abbreviation for day).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'family' becomes 'kin' (synonyms).
'd' put after 'kin' is 'KIND'.
'from' acts as a link.
(Other definitions for kind that I've seen before include "Sort; considerate, friendly" , "Gentle and friendly" , "Tender-hearted" , "Friendly, generous and considerate" , "Loving; class" .)