Sure to change one's ways (6)
I believe the answer is:
routes
'one's ways' is the definition.
'routes' can be an answer for 'ways' (route is a kind of way). I'm not certain of the 'one's' bit.
'sure to change' is the wordplay.
'change' indicates an anagram.
'sure'+'to'='sureto'
'sureto' with letters rearranged gives 'ROUTES'.
Can you help me to learn more?
(Other definitions for routes that I've seen before include "Ways to go for ouster" , "Ways, courses, journeys" , "Ways to go, roads" , "Courses or paths" , "passages" .)