Divorce wife ultimately finds difficult (6)
I believe the answer is:
severe
'difficult' is the definition.
(I've seen this before)
'divorce wife ultimately' is the wordplay.
'divorce' becomes 'sever' (I've seen this before).
'ultimately' indicates one should take the final letters.
The final letter of 'wife' is 'e'.
'sever'+'e'='SEVERE'
'finds' is the link.
(Other definitions for severe that I've seen before include "Taxing" , "Stern or stringent" , "Very plain in style or appearance" , "'Strict, harsh (6)'" , "Grave" .)