A day in Rome (4)
I believe the answer is:
ides
'a day in rome' is the definition.
(Roman calendar term, as in the Ides of March)
This is all the clue.
(Other definitions for ides that I've seen before include "Roman monthly date" , "March day fatal to Julius Caesar" , "Roman calendar day roughly in the middle of the month" , "Eg March 15" , "March 15; dies (anag.)" .)