Rave madly as you declare (4)
I believe the answer is:
aver
'declare' is the definition.
(averring is a kind of declaring)
'rave madly as you' is the wordplay.
'rave' can be anagrammed to 'AVER'.
However, I am unsure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for aver that I've seen before include "Firmly maintain" , "Formally assert" , "Say firmly, rave if necessary" , "Declare to be the case" , "State firmly, maybe rave" .)