March doesn't start over big personality being busy (2,3,2)
I believe the answer is:
on the go
'being busy' is the definition.
('on the go' can be similar in meaning to 'busy')
'march doesn't start over big personality' is the wordplay.
'march' becomes 'Jo' (Jo March is a character in Little Women).
'doesn't start' means to remove the first letter.
'over big' becomes 'nth' (I can't explain this - if you can you should believe this answer much more).
'personality' becomes 'ego' (I've seen this before).
'jo' with its initial letter taken off is 'o'.
'o'+'nth'+'ego'='ON THE GO'
Can you help me to learn more?
(Other definitions for on the go that I've seen before include "Active, always doing something" , "Always busy" , "Very busy, in constant motion" , "Busily active" , "Busy and active" .)