The most common and most likely answer to this crossword clue is the 10 letter word PROPRIETOR
I've seen this crossword clue in Independent
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More clues leading to the result PROPRIETOR
- Support Religious Instruction, uplifting routine for owner
- Landlord in favour of clergyman being denied special old rum, to begin with
- Landlord for publicity that is directed at resistance
- Landlord‘s stewed tripe scoffed by approving soldiers
- Rebel, some might say, backs support for owner
- He holds his own
- Landlord’s supporting institute, shown in report for renovation
- Owner, for one, taken in by erroneous report
Buddy explains!

The straight part
We know that "owner" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case owner = proprietor.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 PROPRIETOR mean?
PROPRIETOR noun- An owner.
- A sole owner of an unincorporated business, also called a sole proprietor.
- One of the owners of an unincorporated business, a partner.
- (history) One or more persons to whom a colonial territory is assigned, like a fief, including its administration.