The most common and most likely answer to this crossword clue is the 4 letter word FART
I've seen this crossword clue in The Guardian
F
A
R
T
Buddy explains!
The straight part
We know that "windbreak" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case windbreak = fart.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 FART mean?
FART noun- An emission of digestive gases from the anus; a flatus.
- (impolite) An irritating person; a fool.
- (impolite, potentially offensive) (usually as "old fart") An elderly person; especially one perceived to hold old-fashioned views.
- (impolite) To emit digestive gases from the anus; to flatulate.
- (usually as "fart around") To waste time with idle and inconsequential tasks; to go about one's activities in a lackadaisical manner; to be lazy or over-relaxed in one's manner or bearing.
- To emit (fumes, gases, etc.).