Relatives reform, being adaptable (9)
I believe the answer is:
versatile
'adaptable' is the definition.
(thesaurus)
'relatives reform' is the wordplay.
'reform' indicates anagramming the letters.
'relatives' anagrammed gives 'VERSATILE'.
'being' is the link.
(Other definitions for versatile that I've seen before include "Relatives able to do many things" , "willing to fit in?" , "Multifaceted" , "Able to adapt" , "Adaptable kind of relatives" .)