The most common and most likely answer to this crossword clue is the 7 plus 2 plus 5 letter word PLASTER OF PARIS
I've seen this crossword clue in The Sunday Telegraph
P
L
A
S
T
E
R
O
F
P
A
R
I
S
More clues leading to the result PLASTER OF PARIS
- Opera star flips out – white powder implicated
- Independent amongst last papers for appraisal – this setter works for breaks
- Profile parts as unusual material for cast
- Material for cast seeing opera stars flip out
- Setter: artless fop, I suspect about average
- French dressing that may be used after break?
- Cast’s material could make opera stars flip insanely
- Dressing by churchgoers briefly cast in this?
- 9, apparently, that should help fix a broken leg
- Setter from France?
Buddy explains!
The straight part
We know that "Setter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case setter = plaster of paris.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.