Poor Maori! No companion in some South American river? (7)
I believe the answer is:
orinoco
'some south american river?' is the definition.
(I've seen this before)
'poor maori no companion in' is the wordplay.
'in' indicates a hidden word.
'ORINOCO' is hidden in the letters of 'poor maori no companion'.
(Other definitions for orinoco that I've seen before include "moves between South American banks" , "South American river flowing into the Atlantic" , "Venezuelan river; one of Wombles" , "large flow of water" , "may be seen running through South America" .)