Criticises Scottish reformer audibly (6)
I believe the answer is:
knocks
'criticises' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for knocks that I've seen before include "Raps; criticises" , "Bangs on door" , "Strikes with a sharp blow or finds fault with" , "Hits" , "criticisms" .)