Grounds for divorce finally, say (6)
I believe the answer is:
estate
'grounds' is the definition.
(I've seen this before)
'divorce finally say' is the wordplay.
'finally' indicates one should take the final letters.
'say' becomes 'state' ('state' can be a synonym of 'say'**).
The final letter of 'divorce' is 'e'.
'e'+'state'='ESTATE'
'for' is the link.
(Other definitions for estate that I've seen before include "Sort of car" , "Piece of land with a lot of houses" , "Land with buildings" , "My wealth" , "Desmene" .)