Outstanding report on fight that's endless (7)
I believe the answer is:
overdue
'outstanding' is the definition.
(I've seen this before)
'on fight that's endless' is the wordplay.
'on' becomes 'over' (I've seen this in other clues).
'fight' becomes 'duel' (dueling is a kind of fighting).
'that's endless' means to remove the last letter.
'duel' with its last letter removed is 'due'.
'over'+'due'='OVERDUE'
'report' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
(Other definitions for overdue that I've seen before include "Late arriving" , "Not having arrived at the expected time" , "after the time specified" , "Opposite of 1 ac." , "Remaining unpaid after the scheduled time" .)