The most common and most likely answer to this crossword clue is the 11 letter word POLTERGEIST
I've seen this crossword clue in The Daily Telegraph
P
O
L
T
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G
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S
T
More clues leading to the result POLTERGEIST
- Lively spirit of new girl initially entering top set?
- Even bits of toilet are seen in prestige production film
- 1980s film contracted Rod Steiger to play Tesla
- Supernatural being got reptiles jittery
- Spirit — reps let it go, being rum
- Labour leader I greet sadly in job, knocking spirit?
- Lost pilot greets one providing a moving experience
- Deciphering Poe’s title originally reveals ghostly spirit
- Presence of poet set girl off
- Exorcist needed to deal with it? Let priest go out
Buddy explains!
The straight part
We know that "knocking spirit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knocking spirit = poltergeist.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 POLTERGEIST mean?
POLTERGEIST noun- An unseen ghost which makes noises and causes disruption, especially by causing physical objects to move or fly about.