The most common and most likely answer to this crossword clue is the 8 letter word MIDFIELD
I've seen this crossword clue in The Guardian
M
I
D
F
I
E
L
D
More clues leading to the result MIDFIELD
Buddy explains!

The straight part
We know that "between defensive lines" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case between defensive lines = midfield.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 MIDFIELD mean?
MIDFIELD noun- The middle of the field of play