War ultimately finishes in tears (5)
I believe the answer is:
rends
'tears' is the definition.
(rending is a kind of tearing)
'war ultimately finishes' is the wordplay.
'ultimately' says to take the final letters.
'finishes' becomes 'ends' ('end' can be a synonym of 'finish').
The last letter of 'war' is 'r'.
'r'+'ends'='RENDS'
'in' is the link.
(Other definitions for rends that I've seen before include "Tears asunder" , "Tears apart" .)