The most common and most likely answer to this crossword clue is the 7 letter word BOOKING
I've seen this crossword clue in The Times
B
O
O
K
I
N
G
Buddy explains!
The straight part
We know that "Caution!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case caution! = booking.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 BOOKING mean?
BOOKING verb- To reserve (something) for future use.
- To write down, to register or record in a book or as in a book.
- (law enforcement) To record the name and other details of a suspected offender and the offence for later judicial action.
- To issue with a caution, usually a yellow card, or a red card if a yellow card has already been issued.
- To travel very fast.
- To record bets as bookmaker.
- (law student slang) To receive the highest grade in a class.
- To leave.
- The act or process of writing something down in a book or books, e.g. in accounting.
- A reservation for a service, such as accommodation in an hotel.
- The engagement of a performer for a particular performance.
- The issuing of a caution which is usually written down in a book, and results in a yellow card or (after two bookings) a red card, that is to say, the player is sent from the field of play.
- The process of photographing, fingerprinting and recording the identifying data of a suspect following arrest.