Go into again (7)
I believe the answer is:
reenter
'go into again' is the definition.
('enter' can be a synonym for 'go into' so perhaps 'reenter' is OK for 'go into again')
This is the entire clue.
(Other definitions for reenter that I've seen before include "Come back inside" , "Go/come in again" , "Penetrate again" , "Go in again" , "Terrene (anag.)" .)