The most common and most likely answer to this crossword clue is the 7 letter word ENTERAL
E
N
T
E
R
A
L
Buddy explains!

The straight part
We know that "one of several plant communities" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one of several plant communities = enteral.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 ENTERAL mean?
ENTERAL adjective- Of, pertaining to, within, or by way of the intestine; enteric.