The most common and most likely answer to this crossword clue is the 6 letter word TONGAN
I've seen this crossword clue in Financial Times
T
O
N
G
A
N
More clues leading to the result TONGAN
- Never to turn back on meeting an islander
- A knight joining secret society on an island
- Islander in trouble not turning up
- Polynesian in Hoxton gang‘s vile cry heard in game
- Hundred turning up to worry islander
- Language used in spacecraft on gantry
- . Transport van's boot is from a Pacific island
- Islander’s not backing horse, after reflection
- Worry not about language
- Foreign national seen in boat on Ganges
Buddy explains!

The straight part
We know that "Islander" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case islander = tongan.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.