The most common and most likely answer to this crossword clue is the 8 letter word COSTMARY
C
O
S
T
M
A
R
Y
More clues leading to the result COSTMARY
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 = costmary.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 COSTMARY mean?
COSTMARY noun- An aromatic plant, Tanacetum balsamita, once used to flavour ale (prior to the use of hops)