Dweller along the Mekong (7)
I believe the answer is:
laotian
'dweller along the mekong' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for laotian that I've seen before include "Citizen of Vientiane, for example" , "Thai neighbour" , "Person from southeast Asian country" , "language out East" , "Oriental" .)