The most common and most likely answer to this crossword clue is the 6 letter word RAZORS
R
A
Z
O
R
S
Buddy explains!

The straight part
We know that "Knives" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knives = razors.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 RAZORS mean?
RAZORS noun- A keen-edged knife of peculiar shape, used in shaving the hair from the face or other parts of the body.
- Any tool or instrument designed for shaving.
- The sharp tusk of a wild boar.
- A conceptual device that allows one to shave away unlikely explanations for a phenomenon.