The most common and most likely answer to this crossword clue is the 6 letter word WALLAH
I've seen this crossword clue in The Times
W
A
L
L
A
H
More clues leading to the result WALLAH
Buddy explains!
The straight part
We know that "one with supervisory role" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one with supervisory role = wallah.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 WALLAH mean?
WALLAH noun- A servant or other person responsible for something, often specified before it, for example kitchen wallah.
- A guy or bloke.
- By God (Allah); may God be my witness used in making a solemn oath