Animosity continued, tribunal failing to reach conclusion (7)
I believe the answer is:
rancour
'animosity' is the definition.
(I've seen this before)
'continued tribunal failing to reach conclusion' is the wordplay.
'continued' becomes 'ran' (running is a kind of continuing).
'tribunal' becomes 'court' (synonyms).
'failing to reach conclusion' means to remove the last letter.
'court' with its last letter removed is 'cour'.
'ran'+'cour'='RANCOUR'
(Other definitions for rancour that I've seen before include "Spiteful hostility" , "Deep-seated bitterness" , "generating ill-feeling ..." , "Bitter feeling or ill will" , "Bitterness and ill will" .)