The most common and most likely answer to this crossword clue is the 8 letter word DESTROYS
I've seen this crossword clue in Financial Times
D
E
S
T
R
O
Y
S
Buddy explains!

The straight part
We know that "Devastates" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case devastates = destroys.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 DESTROYS mean?
DESTROYS verb- To damage beyond use or repair.
- To neutralize, undo a property or condition.
- To put down or euthanize.
- To severely disrupt the well-being of (a person); ruin.
- To defeat soundly.
- To remove data.
- To sing a song poorly.
- (antiphrasis) To exhaust duly and thus recreate or build up.
- To penetrate sexually in an aggressive way.