The most common and most likely answer to this crossword clue is the 6 plus 4 plus 4 letter word DESERT ONES POST
I've seen this crossword clue in Financial Times
D
E
S
E
R
T
O
N
E
S
P
O
S
T
Buddy explains!
The straight part
We know that "Leave station unmanned" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case leave station unmanned = desert ones post.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.