The most common and most likely answer to this crossword clue is the 29 letter word ADJUTATNIESTADJUTANT/NATTIEST
A
D
J
U
T
A
T
N
I
E
S
T
A
D
J
U
T
A
N
T
/
N
A
T
T
I
E
S
T
Buddy explains!
The straight part
We know that "officer/smarter than the rest" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case officer/smarter than the rest = adjutatniestadjutant/nattiest.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.