Unsettled because of endless fighting (7)
I believe the answer is:
overdue
'unsettled' is the definition.
(I've seen this before)
'because of endless fighting' is the wordplay.
'because of' becomes 'over' (eg 'he's upset over it').
'endless' means to remove the last letter.
'fighting' becomes 'duel' (duel is a kind of fighting).
'duel' with its final letter taken off is 'due'.
'over'+'due'='OVERDUE'
(Other definitions for overdue that I've seen before include "Late arriving" , "(Of library books) late" , "Of payment, past the required date" , "Past the ETA" , "Beyond the designated time for payment" .)