States opposed omitting conclusion (5)
I believe the answer is:
avers
'states' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for avers that I've seen before include "States firmly - really raves" , "Alleges, asserts" , "Declares to be true" , "States to be true" , "Swears" .)