Continual stream after Rome is evacuated (9)
I believe the answer is:
recurrent
'continual' is the definition.
('recurrent' can be similar in meaning to 'continual')
'stream after rome is evacuated' is the wordplay.
'stream' becomes 'current' ('current' can be a synonym of 'stream'**).
'after' means one lot of letters go next to another.
'is evacuated' means to remove the middle letters.
'rome' with its centre taken out is 're'.
'current' put after 're' is 'RECURRENT'.
(Other definitions for recurrent that I've seen before include "Occurring repeatedly" , "Coming round repeatedly" , "taking place periodically" , "Happening repeatedly" , "always coming back" .)