Cover ruins, running east (6)
I believe the answer is:
insure
'cover' is the definition.
(I know that cover can be written as insure)
'ruins running east' is the wordplay.
'running' is an anagram indicator.
'east' becomes 'e' (synonyms).
'ruins' with letters rearranged gives 'insur'.
'insur'+'e'='INSURE'
(Other definitions for insure that I've seen before include "Protect value through contract" , "do business at Lloyds?" , "Take out cover" , "Guarantee; make secure" , "Arrange for payment in the event of loss" .)