Month, eg October, not entirely busy (2,3,2)
I believe the answer is:
on the go
'busy' is the definition.
(similar in meaning)
'month eg october not entirely' is the wordplay.
'not entirely' indicates a hidden word.
'ON THE GO' can be found hidden inside 'month eg october'.
(Other definitions for on the go that I've seen before include "Keeping busy, not stopping" , "Always busy" , "Very active (colloq.)" , "Busily active" , "Running around busily" .)