The most common and most likely answer to this crossword clue is the 4 letter word HAPU
H
A
P
U
More clues leading to the result HAPU
Buddy explains!

The straight part
We know that "Maori group" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case maori group = hapu.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does HAPU mean?
HAPU noun- A subtribe of an iwi; the basic political unit within Māori society.