The most common and most likely answer to this crossword clue is the 8 letter word ORIGANUM
I've seen this crossword clue in The Times
O
R
I
G
A
N
U
M
More clues leading to the result ORIGANUM
Buddy explains!
The straight part
We know that "herb" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case herb = origanum.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 ORIGANUM mean?
ORIGANUM noun- Any herbaceous plant of the genus Origanum