Crude antisepsis lacks power, but cleans (9)
I believe the answer is:
sanitises
'cleans' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'crude antisepsis lacks power' is the wordplay.
'crude' indicates an anagram.
'lacks' indicates named letters should be taken away.
'power' becomes 'p' (symbol in physics).
'antisepsis' with 'p' removed is 'antisesis'.
'antisesis' with letters rearranged gives 'SANITISES'.
'but' acts as a link.
Can you help me to learn more?
(Another definition for sanitises that I've seen is " Disinfects".)