Indigenous people from area in eastern part of Honshu (4)
I believe the answer is:
ainu
'indigenous people' is the definition.
(indigenous people of Japan)
'area in eastern part of honshu' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'eastern part of' suggests the final letters (most easterly letter - rightmost).
The last letter of 'honshu' is 'u'.
'a'+'in'+'u'='AINU'
'from' is the link.
(Other definitions for ainu that I've seen before include "aborigines" , "language" , "Big Oriental" , "Japanese person" .)