The most common and most likely answer to this crossword clue is the 9 letter word PALISADED
I've seen this crossword clue in The Times
P
A
L
I
S
A
D
E
D
More clues leading to the result PALISADED
Buddy explains!

The straight part
We know that "fenced in" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fenced in = palisaded.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 PALISADED mean?
PALISADED verb- (usually in the passive) To equip with a palisade.