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

The straight part
We know that "Roman team leader" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case roman team leader = centurion.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 CENTURION mean?
CENTURION noun- An officer of the ancient Roman army, in command of a century of soldiers.
- A player who scores a century.
- A pilot in the United States Navy who has performed 100 night landings on an aircraft carrier.