The most common and most likely answer to this crossword clue is the 9 letter word ESTRANGED
I've seen this crossword clue in The Daily Telegraph
E
S
T
R
A
N
G
E
D
More clues leading to the result ESTRANGED
- Separated garden set to be redeveloped
- Wrong ten grades – not close
- Garden set to go to seed in residence elsewhere?
- Grinding gears tend to become separated
- Andre gets badly alienated
- Separated in forest, rang Edinburgh
- As a mother one doesn’t see and greet son crankily
- Earl getting unexpected note becomes disaffected
- Redesigned garden set apart
- Disaffected editor drinking rum
Buddy explains!

The straight part
We know that "alienated" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case alienated = estranged.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 ESTRANGED mean?
ESTRANGED verb- To cause to feel less close or friendly; alienate. To cease contact with (particularly of a family member or spouse, especially in form estranged).
- To remove from an accustomed place or set of associations.
- Having become a stranger, of one who formerly was close, as a relative, friend, lover, or spouse.