Vietnamese perhaps is like Scot (5)
I believe the answer is:
asian
'vietnamese perhaps' is the definition.
(vietnamese is a kind of Asian)
'like scot' is the wordplay.
'like' becomes 'as'.
'scot' becomes 'ian'.
'as'+'ian'='ASIAN'
'is' is the link.
(Other definitions for asian that I've seen before include "On vast continent" , "One of eastern origin" , "eg Pakistani" , "Of the largest continent" , "One from big continent" .)