A non-believer’s caught out cleanly (7)
I believe the answer is:
aseptic
'cleanly' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I don't see?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for aseptic that I've seen before include "Free from bacteria, surically clean" , "avoiding germs" , "Sterile" , "Free of bacterial or viral contamination" , "Paciest (anag.)" .)