Union gets everybody a nice settlement (8)
I believe the answer is:
alliance
'union' is the definition.
(alliance is a kind of union)
'everybody a nice settlement' is the wordplay.
'everybody' becomes 'all' (I've seen this before).
'settlement' indicates anagramming the letters.
'a'+'nice'='anice'
'anice' with letters rearranged gives 'iance'.
'all'+'iance'='ALLIANCE'
'gets' acts as a link.
(Other definitions for alliance that I've seen before include "Union for mutual benefit" , "Association for mutual benefit" , "League - treaty" , "The joining by political agreement or treaty" , "match?" .)