Guaranteed sore on the outside has healed (7)
I believe the answer is:
secured
'guaranteed' is the definition.
(securing is a kind of guaranteeing)
'sore on the outside has healed' is the wordplay.
'on the outside' means to remove the middle letters.
'has' is a charade indicator (letters next to each other).
'healed' becomes 'cured' ('cure' can be a synonym of 'heal').
'sore' with its centre removed is 'se'.
'se'+'cured'='SECURED'
(Other definitions for secured that I've seen before include "locked up" , "Rescued (anag.)" , "Made safe or fastened safely" , "Seized" , "Got by special effort" .)