The most common and most likely answer to this crossword clue is the 7 letter word WARNING
I've seen this crossword clue in The Guardian
W
A
R
N
I
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G
More clues leading to the result WARNING
Buddy explains!
The straight part
We know that "Advance notice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case advance notice = warning.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 WARNING mean?
WARNING verb- To make (someone) aware of (something impending); especially:
- To caution or admonish (someone) against unwise or unacceptable behaviour.
- (chiefly with "off", "away", and similar words) To advise or order to go or stay away.
- To give warning.
- The action of the verb warn; an instance of warning someone.
- Something spoken or written that is intended to warn.
- Used to warn of danger in signs and notices.