The most common and most likely answer to this crossword clue is the 6 letter word UNWARY
I've seen this crossword clue in Independent
U
N
W
A
R
Y
Buddy explains!

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 UNWARY mean?
UNWARY adjective- Lacking caution as a result of naïveté or inexperience
- Unprepared; not watchful