Go first round to the prison (4)
I believe the answer is:
open
'go' is the definition.
(opening is a kind of going)
'first round to the prison' is the wordplay.
'first' says to put letters next to each other.
'round' becomes 'o' (round can mean a round object).
'to the prison' becomes 'pen' (I've seen this before).
'o' put next to 'pen' is 'OPEN'.
(Other definitions for open that I've seen before include "Ready for business; spread out; manifest" , "ready to entertain new ideas" , "Frank - unsettled" , "Without concealment" , "Frank - ready for business" .)