Said ... "Firm blows to aural organs produce cerumen!" (6)
I believe the answer is:
earwax
'cerumen' is the definition.
(synonyms)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for earwax that I've seen before include "Soft yellow substance secreted by glands of a certain organ" , "Otic secretion" , "Substance accumulating in the lugholes" , "Otic deposit" , "Secretion in the lugholes" .)