The most common and most likely answer to this crossword clue is the 9 letter word PARTERRES
I've seen this crossword clue in The Times
P
A
R
T
E
R
R
E
S
More clues leading to the result PARTERRES
Buddy explains!

The straight part
We know that "Garden areas" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case garden areas = parterres.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 PARTERRES mean?
PARTERRES noun- A flowerbed, particularly an elevated one.
- A garden with paths between such flowerbeds.
- A part of the section of theater seats located on the ground floor, on the same level as the orchestra.
- (by extension) That part of a theater audience seated in the parterre, sometimes regarded as belonging to a lower social class.
- An apartment balcony.