The most common and most likely answer to this crossword clue is the 8 letter word PORTENDS
P
O
R
T
E
N
D
S
Buddy explains!

The straight part
We know that "Warnings" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warnings = portends.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 PORTENDS mean?
PORTENDS verb- To serve as a warning or omen of.
- To signify; to denote.