Country starts to insist railways are nationalised (4)
I believe the answer is:
iran
'country' is the definition.
(Iran is a country)
'starts to insist railways are nationalised' is the wordplay.
'starts to' says to take the initial letters.
The initial letters of 'insist railways are nationalised' is 'IRAN'.
(Other definitions for iran that I've seen before include "Tehran is its capital" , "Middle Eastern country" , "Country where the official language is Farsi" , "Middle East Islamic republic" , "foreign land" .)