The most common and most likely answer to this crossword clue is the 7 letter word PORTICO
I've seen this crossword clue in Financial Times
P
O
R
T
I
C
O
More clues leading to the result PORTICO
- Left religious painting unfinished that's covered entrance
- Left in charge of old architectural feature
- One firm behind left entrance
- Left company outside one entrance to building
- Building extension, incomplete image on the left side
- Architectural feature I see in European city
- Arcade I entered south of Calais, maybe needing company
- Left in charge of building construction
- One about to enter Iberian FC entrance
- Left cut-down picture in colonnade
Buddy explains!

The straight part
We know that "entrance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case entrance = portico.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 PORTICO mean?
PORTICO noun- A porch, or a small space with a roof supported by columns, serving as the entrance to a building.