The most common and most likely answer to this crossword clue is the 7 letter word NOTHING
N
O
T
H
I
N
G
More clues leading to the result NOTHING
- No good fastening in old, flimsy zip
- Recording about husband's love
- What’s hard in writing down cipher
- Love new concoction of hot gin
- Love can mean this on flipping stormy night
- Zero marking when first piece of homework’s put in
- An hour being absorbed, observing a duck
- O no! Awful night!
- With husband in heart, indicating love
- Love alcoholic drink that’s kept diluted
Buddy explains!

The straight part
We know that "O" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case o = nothing.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 NOTHING mean?
NOTHING noun- Something trifling, or of no consequence or importance.
- A trivial remark (especially in the term sweet nothings).
- A nobody (insignificant person).
- Not at all; in no way.
- Not any thing; no thing.
- An absence of anything, including empty space, brightness, darkness, matter, or a vacuum.