The most common and most likely answer to this crossword clue is the 5 letter word YPRES
I've seen this crossword clue in Independent
Y
P
R
E
S
More clues leading to the result YPRES
- Scene of action initially settled on years before
- Battle site is somewhat muddy, presumably
- Scene of fighting – push not ending after year
- Battlefield in Normandy preserved
- Battles to unwrap birthday present
- Pair in quite a battle
- Section in highly prestigious battle site
- World War I battle certainly captivates pair
- Belgian village among cypresses
Buddy explains!

The straight part
We know that "Battle site" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case battle site = ypres.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.