Asian swallow flying west across India gradually disappears (9)
I believe the answer is:
taiwanese
'asian' is the definition.
(I know that Taiwanese is a type of asian)
'swallow flying west across india gradually disappears' is the wordplay.
'swallow' becomes 'eat' (swallow can mean to consume or eat up).
'flying west' is a reversal indicator (letters written right to left or east to west).
'across' indicates putting letters inside.
'india' becomes 'i' (phonetic alphabet: alpha, bravo, charlie etc.).
'gradually disappears' becomes 'wanes' (to wane is to disappear over time).
'eat' backwards is 'tae'.
'i'+'wanes'='iwanes'
'tae' placed around 'iwanes' is 'TAIWANESE'.
(Other definitions for taiwanese that I've seen before include "oriental in character" , "Chinese" , "Coming from Taipei?" , "from Asia" , "Eg, native to Taipei" .)