Fixes unstarted conclusions (4)
I believe the answer is:
ends
'conclusions' is the definition.
(end is a kind of conclusion)
'fixes unstarted' is the wordplay.
'fixes' becomes 'mends' ('mend' can be a synonym of 'fix').
'unstarted' means to remove the first letter.
'mends' with its first letter taken away is 'ENDS'.
(Other definitions for ends that I've seen before include "Poles, aims" , "passes away" , "Final parts" , "Stops in dens" , "Halts" .)