The most common and most likely answer to this crossword clue is the 5 letter word MAORI
I've seen this crossword clue in The Guardian
M
A
O
R
I
More clues leading to the result MAORI
- I wander back to see Antipodean people
- Roam over island for the language?
- Polynesian mother, or yours truly
- I wander uphill to see native New Zealander
- Language degree press endlessly sent up
- New Zealander chairman oddly missing train
- Wander over island, one in NZ
- I travel uphill to find native
- Ramble contrarily, having only one language abroad
- One with force reflected about love for language
Buddy explains!

The straight part
We know that "one in NZ" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one in nz = maori.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.