The most common and most likely answer to this crossword clue is the 10 letter word DETACHMENT
I've seen this crossword clue in Financial Times
D
E
T
A
C
H
M
E
N
T
More clues leading to the result DETACHMENT
Buddy explains!

The straight part
We know that "Unit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unit = detachment.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 DETACHMENT mean?
DETACHMENT noun- The action of detaching; separation.
- The state of being detached or disconnected; insulation.
- Indifference to the concerns of others; disregard; nonchalance; aloofness.
- Absence of bias; impartiality; objectivity.
- The separation of a military unit from the main body for a particular purpose or special mission.
- The unit so dispatched.
- A permanent unit organized for special duties.
- Any smaller portion of a main body separately employed.