The most common and most likely answer to this crossword clue is the 8 letter word MUST-SEE
I've seen this crossword clue in The Guardian
M
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S
T
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S
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More clues leading to the result MUST-SEE
Buddy explains!
The straight part
We know that "essential item for visitor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case essential item for visitor = must-see.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 MUST-SEE mean?
MUST-SEE noun- Anything unmissably good, such as a film or television programme or a tourist attraction
- Unmissably good