Move good into Cornish town (5)
I believe the answer is:
budge
'move' is the definition.
(to budge is to move slightly)
'good into cornish town' is the wordplay.
'good' becomes 'g' (abbreviation).
'into' indicates putting letters inside.
'cornish town' becomes 'bude' (I can't justify this - if you can you should give a lot more credence to this answer).
'g' placed into 'bude' is 'BUDGE'.
Can you help me to learn more?
(Other definitions for budge that I've seen before include "Move unwillingly" , "Cause to alter an opinion or stance, shift" , "Change an opinion" , "Shift or yield" , "Move however slightly" .)