The most common and most likely answer to this crossword clue is the 8 letter word OKLAHOMA
I've seen this crossword clue in The Times
O
K
L
A
H
O
M
A
More clues leading to the result OKLAHOMA
- Musical cellist is after satisfactory note at heart of show
- Look, a ham must be ordered, OK
- Agreed: US city’s mostly in American state
- Musical in which very good French article mentioned Mr Simpson
- In brief, fine state of musical theatre
- Musical would be fine, if shortened
- Musical territory initially extended!
- Average priest locking up house in US state
- It’s OK if one wants an abbreviation
- Musical note held by fine old mum
Buddy explains!

The straight part
We know that "OK" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ok = oklahoma.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.