Aver (6)
'aver' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for assert that I've seen before include "State firmly, aver" , "Declare, state vigorously" , "Affirm, allege" , "Declare or affirm" , "Aver, declare" .)
'aver' is the definition.
(declaring is a kind of avering)
This is all the clue.
(Other definitions for declare that I've seen before include "Announce 13 closed" , "Proclaim" , "Assert" , "Profess" , "Aver, state" .)