Claim everything, for example, before end of marriage (6)
I believe the answer is:
allege
'claim' is the definition.
(thesaurus)
'everything for example before end of marriage' is the wordplay.
'everything' becomes 'all' (I've seen this before).
'for example' becomes 'eg' ('e.g.' can be a synonym of 'for example').
'before' says to put letters next to each other.
'end of' indicates one should take the final letters.
The final letter of 'marriage' is 'e'.
'all'+'eg'+'e'='ALLEGE'
(Other definitions for allege that I've seen before include "Declare without actual proof" , "Aver (without proof)" , "Declare or assert without proof" , "Claim (a person is guilty)" , "Accuse without established proof" .)