Decide to terminate (8)
I believe the answer is:
conclude
This clue is a double definition.
'decide' is the first definition.
(I've seen this before)
'terminate' is the second definition.
(concluding is a kind of terminating)
'to' acts as a link.
(Other definitions for conclude that I've seen before include "Decide by reasoning or come to a close" , "Deduce - end" , "Bring to a close" , "Finish - deduce" , "Infer or bring to an end" .)