Fixed up in last marriage (8)
I believe the answer is:
nuptials
'marriage' is the definition.
(thesaurus)
'fixed up in last' is the wordplay.
'fixed' is an anagram indicator.
'up'+'in'+'last'='upinlast'
'upinlast' anagrammed gives 'NUPTIALS'.
(Other definitions for nuptials that I've seen before include "Marriage ceremony" , "Wedding - suit plan (anag)" , "Wedding ceremony" , "A wedding or marriage" , "Marriage ceremonies" .)