The most common and most likely answer to this crossword clue is the 8 letter word CAUTIONS
I've seen this crossword clue in The Daily Telegraph
C
A
U
T
I
O
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S
Buddy explains!

The straight part
We know that "Warnings from police" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warnings from police = cautions.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 CAUTIONS mean?
CAUTIONS noun- Precept or warning against evil or danger of any kind; exhortation to wariness; advice; injunction; prudence in regard to danger; provident care
- A careful attention to the probable effects of an act, in order that failure or harm may be avoided
- Security; guaranty; bail.
- One who draws attention or causes astonishment by their behaviour.
- A formal warning given as an alternative to prosecution in minor cases.
- A yellow card.
- To warn; to alert, advise that caution is warranted.
- To give a yellow card