Something that echoes treason or showing corruption (9)
I believe the answer is:
resonator
'showing corruption' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'something that echoes treason' is the wordplay.
I cannot really see how this works, but
an anagram of 'treason' is 'resonat' which is present in the answer.
The remaining letters 'or' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'or' acts as a link.
Can you help me to learn more?
(Other definitions for resonator that I've seen before include "Sounding vessel" , "Device for enhancing oscillations" , "Tuned circuitry" , "Device amplifying sound" .)