Mixer thus could finish a conflict without the Maori (4-5)

'mixer' is the definition.
(I've seen this before)

'thus could finish a conflict without the maori' is the wordplay.
'thus' becomes 'so' (synonyms).
'finish' suggests the final letters.
'conflict' becomes 'war' (war is a kind of conflict).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'the maori' becomes 'te' (I've seen this in other clues).
The last letter of 'could' is 'd'.
'war' enclosing 'te' is 'water'.
'so'+'d'+'a'+'water'='SODA-WATER'