Asian involved Sean in joke (8)
I believe the answer is:
japanese
'asian' is the definition.
(Japanese is an example)
'involved sean in joke' is the wordplay.
'involved' indicates anagramming the letters (involved can mean confusing or complex).
'in' indicates putting letters inside.
'joke' becomes 'jape' (synonyms).
'sean' with letters rearranged gives 'anes'.
'anes' going inside 'jape' is 'JAPANESE'.
(Other definitions for japanese that I've seen before include "Nipponese" , "Asian people" , "Shinto their religion" , "This nationality uses a Nasa jeep incorrectly" , "Native to Tokyo, say" .)