Tries lies out to remove germs (9)
I believe the answer is:
sterilise
'to remove germs' is the definition.
'tries lies out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'tries'+'lies'='trieslies'
'trieslies' is an anagram of 'STERILISE'.
(Other definitions for sterilise that I've seen before include "Make free from bacteria" , "Free from germs" , "Make free from micro-organisms, like surgeon's knife" , "Disinfect" , "Listerise (anag)" .)