The most common and most likely answer to this crossword clue is the 5 plus 6 plus 4 letter word ROYAL ALBERT HALL
I've seen this crossword clue in The Daily Telegraph
R
O
Y
A
L
A
L
B
E
R
T
H
A
L
L
More clues leading to the result ROYAL ALBERT HALL
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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.