Resist plan for relative (6)
I believe the answer is:
sister
'for relative' is the definition.
(sister is a kind of relative)
'resist plan' is the wordplay.
'plan' is an anagram indicator (plan can mean organise).
'resist' anagrammed gives 'SISTER'.
(Other definitions for sister that I've seen before include "trade union member?" , "Senior nurse; relative" , "The nurse in charge" , "habits' - one who has them" , "woman in hospital" .)