Cryptic crossword clue
Royal Opera House deployed piano only, a real sleep inducer 8

The most common and most likely answer to this crossword clue is the 8 letter word ROHYPNOL

I've seen this crossword clue in The Times
R
O
H
Y
P
N
O
L

Buddy explains!

The straight part
We know that "a real sleep inducer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a real sleep inducer = rohypnol.
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.

Crossword Answer definitions

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