The most common and most likely answer to this crossword clue is the 6 letter word BAMBOO
I've seen this crossword clue in The Daily Telegraph
B
A
M
B
O
O
More clues leading to the result BAMBOO
- Deer one leaves loves woody grass
- Grass skirts from Burma, low around back initially
- Mob boa wriggling in grass
- Baby deer mostly loves grass
- Type of grass that makes boob wobble about in the morning
- Plant a bomb, explosive gas
- In leaving child, love hollow stuff
- Grass to throw, only two thirds
- Possibly shoots ducks with graduate doctor
- Just over half of conmen grass
Buddy explains!

The straight part
We know that "it’s hollow-stemmed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s hollow-stemmed = bamboo.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 BAMBOO mean?
BAMBOO noun- A grass of the Poaceae family, characterised by its woody, hollow, round, straight, jointed stem, all of which are in the Bambuseae tribe.
- The wood of the bamboo plant as a material or cane.
- A didgeridoo.
- A member of the British military or British East India Company who spent so much time in Indonesia, India, or Malaysia that they never went back home.
- To flog with a bamboo cane.
- To paint (furniture, etc.) to give it the appearance of bamboo.
- To penetrate sexually.
- Made of the wood of the bamboo.