The Maori existed on leftovers (5)
I believe the answer is:
waste
'leftovers' is the definition.
(I have seen 'Useless leftovers ' mean 'waste' so perhaps 'leftovers' could also mean 'waste')
'the maori existed on' is the wordplay.
'the maori' becomes 'te' (I've seen this in other clues).
'existed' becomes 'was' ('be' can be a synonym of 'exist').
'on' says to put letters next to each other.
'te' put after 'was' is 'WASTE'.
(Other definitions for waste that I've seen before include "Not use effectively" , "Misuse" , "Fritter away" , "unused" , "Rubbish, barren land" .)