One can be intolerant, if one is so minded! (6)
I believe the answer is:
narrow
'one can' is the definition.
The definition and answer can be both related to change as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for narrow that I've seen before include "Become restricted" , "Circumscribed" , "Restrict" , "... not one" , "Strait, not wide" .)