Rule out solution already hinted at when editor returned (8)
I believe the answer is:
preclude
'rule out' is the definition.
(synonyms)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for preclude that I've seen before include "Make impossible" , "Obviate, prevent" , "Prevent, forestall the possibility of" , "Debar" , "Prevent, prohibit" .)