The most common and most likely answer to this crossword clue is the 6 letter word DROMOS
D
R
O
M
O
S
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The straight part
We know that "Entry passage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case entry passage = dromos.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 DROMOS mean?
DROMOS noun- An avenue, especially in Ancient Greece.
- A walkway to a building, a ceremonial walkway to a temple or tomb in Ancient Greece or Egypt.
- A racecourse, especially in Ancient Greece.