I clean out wound to protect against infection (9)
I believe the answer is:
inoculate
'protect against infection' is the definition.
(inoculation protects against infection)
'i clean out wound' is the wordplay.
'wound' indicates an anagram (wound can mean twisted or turned around).
'clean'+'out'='cleanout'
'cleanout' is an anagram of 'noculate'.
'i'+'noculate'='INOCULATE'
'to' acts as a link.
(Other definitions for inoculate that I've seen before include "Graft" , "Treat with a vaccine or serum" , "Give a jab" , "Immunise, vaccinate" , "Introduce an idea or attitude into the mind of: immunise" .)