Clay under mountain grand for Asian (7)
I believe the answer is:
bengali
'asian' is the definition.
(native of Bengal)
'clay under mountain grand' is the wordplay.
'clay' becomes 'ali' (Muhammad Ali was born Cassius Clay).
'under' is a charade indicator (letters next to each other).
'mountain' becomes 'ben' (ben is a kind of mountain**).
'grand' becomes 'g' ('G' can be a synonym of 'grand').
'ben'+'g'='beng'
'ali' after 'beng' is 'BENGALI'.
'for' is the link.
(Other definitions for bengali that I've seen before include "tongue" , "Ethnic group and language of NE Indian subcontinent" , "may be Indian" , "Indic language" , "From Dhaka or Kolkata, perhaps" .)