Bring to a premature end (5)
I believe the answer is:
abort
'bring to a premature end' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for abort that I've seen before include "Call off (mission) because of problem" , "Bring to premature conclusion" , "[FINISH] prematurely" , "End prematurely" , "Terminate prematurely" .)