Sum a union distributed as agreed (9)
I believe the answer is:
unanimous
'agreed' is the definition.
(thesaurus)
'sum a union distributed' is the wordplay.
'distributed' indicates an anagram.
'sum'+'a'+'union'='sumaunion'
'sumaunion' with letters rearranged gives 'UNANIMOUS'.
'as' acts as a link.
(Other definitions for unanimous that I've seen before include "in complete agreement" , "Without one dissenter" , "With one mind" , "Acting together" , "without dissent" .)