Curse former wife before end of divorce case (8)
I believe the answer is:
execrate
'curse' is the definition.
(thesaurus)
'former wife before end of divorce case' is the wordplay.
'former wife' becomes 'ex'.
'before' says to put letters next to each other.
'end of' indicates one should take the final letters.
'case' becomes 'crate' (I've seen this before**).
The final letter of 'divorce' is 'e'.
'ex'+'e'+'crate'='EXECRATE'
(Other definitions for execrate that I've seen before include "Inveigh against" , "Denounce or detract" , "Express hatred for" , "Damn" , "'Abhor, find repugnant (8)'" .)