The most common and most likely answer to this crossword clue is the 5 letter word THYME
I've seen this crossword clue in The Guardian
T
H
Y
M
E
More clues leading to the result THYME
- Your tip for marinade? Eastern herb
- Your old setter, one going to pot?
- The enemy heard something fragrant?
- Ingredient of healthy meals?
- Tasty plant is a passing phenomenon, we hear
- Herb forming part of healthy meal
- They say season with herb
- Aromatic plant in porridge, reportedly?
- Herb gets the no. 4 to Scarborough Fair
- Herb, a healer by the sound of it?
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 = thyme.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 THYME mean?
THYME noun- Any plant of the labiate genus Thymus, such as the garden thyme, Thymus vulgaris, a warm, pungent aromatic, that is much used to give a relish to seasoning and soups.