The most common and most likely answer to this crossword clue is the 8 letter word AMENABLE
I've seen this crossword clue in The Times
A
M
E
N
A
B
L
E
More clues leading to the result AMENABLE
- Accommodating chaps after a black filling beer
- Open noodles next to desk, skipping starters
- Willing troops accompanying sailor in the drink
- Awfully mean bachelor cracks beer open
- Willing scholar comes up to help
- Last word by competent subject
- 24 Willing in the morning to empower
- A people fit and willing
- Woman during stroll open to suggestion
- Flexible, fit American guys in the lead
Buddy explains!

The straight part
We know that "Open" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case open = amenable.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 AMENABLE mean?
AMENABLE adjective- Willing to respond to persuasion or suggestions.
- Willing to comply; easily led.
- Liable to be brought to account; responsible; accountable.
- (of a group) Being a locally compact topological group carrying a kind of averaging operation on bounded functions that is invariant under translation by group elements.