The most common and most likely answer to this crossword clue is the 10 letter word BEANSTALKS
I've seen this crossword clue in The Daily Telegraph
B
E
A
N
S
T
A
L
K
S
More clues leading to the result BEANSTALKS
Buddy explains!

The straight part
We know that "tall plants" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tall plants = beanstalks.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 BEANSTALKS mean?
BEANSTALKS noun- The stem of a bean plant, proverbially fast-growing and tall.
- (by extension) A tall, slim person.
- A space elevator.