Fit brief (6)
I believe the answer is:
inform
This clue could be a double definition.
'fit' is the first definition.
The answer and definition can be both related to change as well as being verbs in their base form.
Maybe they are linked in a way I don't understand?
'brief' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for inform that I've seen before include "snitch?" , "Advise, acquaint with" , "effective" , "Notify or tell" , "Put wise" .)