In Baltimore a road back (4)
I believe the answer is:
rear
'back' is the definition.
(I know that back can be written as rear)
'in baltimore a road' is the wordplay.
'in' indicates the answer is hidden within the clue.
'REAR' is hidden in the letters of 'baltimore a road'.
(Other definitions for rear that I've seen before include "Buck" , "Raise - back" , "The back part of something" , "Rare at the back" , "Bring up - the tail" .)