Eastern relation is eccentric (8)
I believe the answer is:
oriental
'eastern' is the definition.
(synonyms)
'relation is eccentric' is the wordplay.
'is eccentric' is an anagram indicator.
'relation' with letters rearranged gives 'ORIENTAL'.
(Other definitions for oriental that I've seen before include "Relation? (anagram)" , "Of the eastern or Asian world" , "Maybe Chinese" , "Eastern sort of relation" , "Non-European" .)