I think America should return land to its natives (5)
I believe the answer is:
suomi
'land to its natives' is the definition.
(I've seen this before)
'i think america should return' is the wordplay.
'i think' becomes 'imo' (abbreviation for 'in my opinion').
'america' becomes 'US' (United States).
'should return' is a reversal indicator.
'imo'+'us'='imous'
'imous' reversed gives 'SUOMI'.
(Other definitions for suomi that I've seen before include "Finland in Finnish" , "Finnish language; I sumo (anag.)" , "land to its natives" , "Country" .)