Country, near ruin at intervals, that's on the rise (4)
I believe the answer is:
iran
'country' is the definition.
(Iran is a country)
'near ruin at intervals that's on the rise' is the wordplay.
'at intervals' indicates alternate letters (letters are taken at regular intervals).
'that's on the rise' shows that the letters should be reversed in order (in a down clue, letters go up).
'near'+'ruin'='nearruin'
The alternate letters of 'nearruin' are 'nari'.
'nari' back-to-front is 'IRAN'.
(Other definitions for iran that I've seen before include "Islamic republic on the Persian Gulf" , "Tehran's country" , "Persia some time ago" , "Middle Eastern country" , "Former Persia" .)