Persists and has good relationship (4,2)
I believe the answer is:
gets on
'persists' is the definition.
The answer and definition can be both related to change as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'has good relationship' is the wordplay.
'has' becomes 'gets' ('get' can be a synonym of 'have').
'good relationship' becomes 'on' (I can't explain this - if you can you should believe this answer much more).
'gets'+'on'='GETS ON'
'and' acts as a link.
Can you help me to learn more?
(Another definition for gets on that I've seen is " Makes progress".)