The most common and most likely answer to this crossword clue is the 10 letter word BACKSTAIRS
I've seen this crossword clue in The Times
B
A
C
K
S
T
A
I
R
S
More clues leading to the result BACKSTAIRS
Buddy explains!

The straight part
We know that "behind the scenes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case behind the scenes = backstairs.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 BACKSTAIRS mean?
BACKSTAIRS noun- A staircase at the rear of a building or one normally only used by servants and tradesmen.
- An indirect or furtive means of access or intercourse.
- Secret or furtive.
- Scandalous.