The most common and most likely answer to this crossword clue is the 10 letter word LIEUTENANT
I've seen this crossword clue in The Times
L
I
E
U
T
E
N
A
N
T
More clues leading to the result LIEUTENANT
- What’s eaten until turning rank
- Relax with posh lodger and officer
- European Union figure in translation of Latin, rank
- . Junior officer renting French place?
- Toilet renter reported an American officer
- Officer’s story on truck supported by northern worker
- Deputy picked up socialist resident
- Rank
- Officer’s story has you speaking to social worker after bag is returned
- In place of “occupier” see “officer”
Buddy explains!

The straight part
We know that "officer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case officer = lieutenant.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 LIEUTENANT mean?
LIEUTENANT noun- The lowest Junior Commissioned Officer rank(s) in many military forces, often Army and Marines.
- A person who manages or executes the plans and directives of another, more senior person - i.e. a manager to his director.
- The second-in-command (2IC) of a group.
- A military grade that is junior to the grade the adjective modifies: lieutenant colonel, lieutenant general, lieutenant commander.