Change one's mind; abate (6)
I believe the answer is:
relent
This clue is a double definition.
'change one's mind' is the first definition.
(to relent is to give in or change one's mind)
'abate' is the second definition.
(I've seen this in another clue)
(Other definitions for relent that I've seen before include "Become less stern than intended" , "Become less severe, soften" , "Come round" , "Decide to be kind after all?" , "Become less intense" .)