Snake seen in Rome and Eritrea (7)
I believe the answer is:
meander
'snake' is the definition.
(I know that snake is a kind of meander)
'in rome and eritrea' is the wordplay.
'in' says the answer is hidden in the clue.
'MEANDER' is hidden in the letters of 'rome and eritrea'.
'seen' acts as a link.
(Other definitions for meander that I've seen before include "Wander without aim or direction" , "Renamed in order to wander in leisurely way" , "an Indo-European river" , "Wind (like a river)" , "Wander about, follow a winding course" .)