Clean out potty with iodine to prevent infection (9)
I believe the answer is:
inoculate
'to prevent infection' is the definition.
(I've seen this before)
'clean out potty with iodine' is the wordplay.
'potty with' indicates an anagram.
'iodine' becomes 'I' (chemical symbol).
'clean'+'out'='cleanout'
'cleanout' with its letters mixed up with 'i' gives 'INOCULATE'.
(Other definitions for inoculate that I've seen before include "Treat with a vaccine or serum" , "to prevent infection" , "Introduce an idea or attitude into the mind of: immunise" , "Immunise, vaccinate" , "Inject against a disease" .)