The most common and most likely answer to this crossword clue is the 5 letter word MAJOR
I've seen this crossword clue in The Times
M
A
J
O
R
More clues leading to the result MAJOR
- Mother and girl finding way round doctor and chief steward
- Officer in spot of trouble retreating with men
- Obliged you very informally to listen to officer
- Officer to stick around other ranks
- Trouble over gold key
- Officer to harm little woman in custody
- Tory leader‘s opposed to miner in speech
- One PM at one time is one one above one
- Stick around with Gold, an American student
- A great prime minister?
Buddy explains!

The straight part
We know that "chief steward" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chief steward = major.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 MAJOR mean?
MAJOR noun- A military rank between captain and lieutenant colonel.
- The main area of study of a student working toward a degree at a college or university.
- A student at a college or university concentrating on a given area of study.
- A person of legal age.
- The major premise.
- A touchdown, or major score.
- A large, commercially successful company, especially a record label that is bigger than an indie.
- (British slang) An elder brother (especially at a public school).
- A large leaf-cutter ant that acts as a soldier, defending the nest.
- To concentrate on a particular area of study as a student in a college or university
- Of great significance or importance.
- Greater in number, quantity, or extent
- Of full legal age, having attained majority
- Of a scale that follows the pattern: tone - tone - semitone - tone - tone - tone - semitone
- Being the larger of two intervals denoted by the same ordinal number.
- Containing the note a major third (four half steps) above the tonic.
- (campanology) Bell changes rung on eight bells.