The most common and most likely answer to this crossword clue is the 6 letter word OATERS
I've seen this crossword clue in Independent
O
A
T
E
R
S
More clues leading to the result OATERS
Buddy explains!

The straight part
We know that "stetsons required in these!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stetsons required in these! = oaters.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 OATERS mean?
OATERS noun- (entertainment) A movie or television show about cowboy or frontier life; a western movie.