The most common and most likely answer to this crossword clue is the 9 letter word DISTANCED
I've seen this crossword clue in The Guardian
D
I
S
T
A
N
C
E
D
More clues leading to the result DISTANCED
Buddy explains!

The straight part
We know that "Detached" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case detached = distanced.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 DISTANCED mean?
DISTANCED verb- To move away (from) someone or something.
- To leave at a distance; to outpace, leave behind.