Some petunias raised by indigenous Japanese people (4)
I believe the answer is:
ainu
'indigenous japanese people' is the definition.
'some petunias raised' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'raised' is a reversal indicator.
'unia' is hidden within 'petunias'.
'unia' backwards is 'AINU'.
'by' is the link.
(Other definitions for ainu that I've seen before include "Big Oriental" , "aborigines" , "Japanese person" , "language" .)