Country west of Vietnam (4)
I believe the answer is:
laos
'country west of vietnam' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for laos that I've seen before include "Mountainous state in southeastern Asia" , "Landlocked south-east Asian country" , "Indo-Chinese country" , "South-east Asian republic, capital Vientiane" , "Country of SE Asia" .)