Asian language proves draw by the sound of it (4)
I believe the answer is:
thai
'asian language' is the definition.
(language of Thailand)
'draw by the sound of it' is the wordplay.
'draw' becomes 'tie' (synonyms).
'by the sound of it' shows a homophone (sound like).
'tie' is a homophone of 'THAI'.
'proves' acts as a link.
(Other definitions for thai that I've seen before include "eastern language" , "Native of Southeast Asia" , "An Asian cuisine" , "countryman" , "Asian language" .)