A starter bound not to get on (3)
I believe the answer is:
bud
'get on' is the definition.
The answer and definition can be both related to change as well as being verbs in their base form.
Perhaps you can see a link between them that I don't see?
'a starter bound not' is the wordplay.
'a starter' suggests taking the first letters.
'not' becomes 'ud' (I can't justify this - if you can you should believe this answer much more).
The initial letter of 'bound' is 'b'.
'b'+'ud'='BUD'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for bud that I've seen before include "Tight flower" , "Small knob that will develop into a leaf or flower" , "mate in America" , "American beer" , "Undeveloped flower" .)