Busy, busy (2,3,2)
I believe the answer is:
on the go
'busy busy' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for on the go that I've seen before include "Running around busily" , "Very active (colloq.)" , "Active, always doing something" , "Active and energetic" , "Busily active" .)