The most common and most likely answer to this crossword clue is the 13 letter word VEGGIE-BURGER
I've seen this crossword clue in The Times
V
E
G
G
I
E
-
B
U
R
G
E
R
Buddy explains!
The straight part
We know that "non-meat option" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case non-meat option = veggie-burger.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.