The most common and most likely answer to this crossword clue is the 2 plus 5 letter word ST LUCIA
I've seen this crossword clue in The Daily Telegraph
S
T
L
U
C
I
A
More clues leading to the result ST LUCIA
- Sail cut off somewhere in the W Indies
- Excellent sects from the east in island nation
- Country‘s spies turned, lust comes first
- First class fashions coming from South Island
- Secretly, Thai cult spread over island
- Island with flipping immaculate religious sects
- Island capital with unorthodox religion’s rebuffed
- Island‘s one sect backed in South Africa
- Country's spies turned, lust comes first
- Member of West Indies cult movement, one embraced by South America
Buddy explains!

The straight part
We know that "Island" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case island = st lucia.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.