Change one's mind and support course (9)
I believe the answer is:
backtrack
'change one's mind' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how one could define the other.
'support course' is the wordplay.
'support' becomes 'back' (to back is to support or endorse).
'course' becomes 'track' (synonyms).
'back'+'track'='BACKTRACK'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for backtrack that I've seen before include "Retrace one's steps" , "Withdraw" , "Return, retract" , "Reverse one's decision" , "Climb down" .)