The most common and most likely answer to this crossword clue is the 7 letter word INGRESS
I've seen this crossword clue in The Times
I
N
G
R
E
S
S
More clues leading to the result INGRESS
- In grand gown daughter walks making entrance
- Entrance made by different singers
- French artist originally snubbed opening
- French painter’s entry
- Entrance painter with head of sylph
- Entrance painter with the ultimate in masterpieces
- French painter’s admission
- Entrance of French painter to society
- Doctor resigns as a way of introduction
- French artist heading for stage door
Buddy explains!

The straight part
We know that "opening" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case opening = ingress.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 INGRESS mean?
INGRESS noun- The act of entering.
- Permission to enter.
- A door or other means of entering.
- The entrance of the Moon into the shadow of the Earth in eclipses, or the Sun's entrance into a sign, etc.
- To intrude or insert oneself
- To enter (a specified location or area)
- (of a planet) To enter into a zodiacal sign
- To manifest or cause to be manifested in the temporal world; to effect ingression