Terribly earnest Oriental (7)
I believe the answer is:
eastern
'oriental' is the definition.
(synonyms)
'terribly earnest' is the wordplay.
'terribly' indicates anagramming the letters.
'earnest' with letters rearranged gives 'EASTERN'.
(Other definitions for eastern that I've seen before include "Asian" , "Nearest (anag) - oriental" , "See 11" , "Earnest (anag.)" , "in Beijing, possibly" .)