The most common and most likely answer to this crossword clue is the 4 letter word EYOT
I've seen this crossword clue in Independent
E
Y
O
T
More clues leading to the result EYOT
- Where one’s isolated? That’s up to you
- Crew said something at Chiswick in boat race
- Eliot's first play about small island
- Eastern play about small island
- Defy youth at regular intervals in small island
- Model European climbing small island
- Play up after opening of Easter Island
- Feature of river at Chiswick had to be broadcast
- Return plaything to European island
- A glimpse of Alderney — otherworldly island
Buddy explains!

The straight part
We know that "small island" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case small island = eyot.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 EYOT mean?
EYOT noun- A little island, especially in a river or lake.