The most common and most likely answer to this crossword clue is the 6 letter word BESETS
I've seen this crossword clue in The Daily Telegraph
B
E
S
E
T
S
More clues leading to the result BESETS
Buddy explains!

The straight part
We know that "Attacks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case attacks = besets.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 BESETS mean?
BESETS verb- To surround or hem in.
- (sometimes figurative) To attack or assail, especially from all sides.
- To decorate something with jewels etc.
- Of a ship, to get trapped by ice.