The most common and most likely answer to this crossword clue is the 8 letter word ARCHWAYS
I've seen this crossword clue in Financial Times
A
R
C
H
W
A
Y
S
Buddy explains!

The straight part
We know that "Entrances" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case entrances = archways.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 ARCHWAYS mean?
ARCHWAYS noun- A passageway covered by an arch, particularly one made of masonry.
- A doorway with a semilunar-shaped top.