The most common and most likely answer to this crossword clue is the 9 letter word MARIJUANA
I've seen this crossword clue in Independent
M
A
R
I
J
U
A
N
A
More clues leading to the result MARIJUANA
- One Spaniard carrying another pot
- Girl with Spanish boy smuggled in drugs
- In Barcelona Mary embraces John in grass
- Spanish woman has Spanish man in grass
- Spoil writer John, in Spain, acquiring a pot
- Pot made by Spanish girl, broken by Spanish boy
- Tea for uplifting mood in the morning, sipped by Juan? The opposite
- Crowd retreats, heading away from Mexican city plant
Buddy explains!

The straight part
We know that "grass" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case grass = marijuana.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 MARIJUANA mean?
MARIJUANA noun- A drug smoked or ingested for euphoric effect, cannabis.
- The hemp plant itself, Cannabis sativa.