The most common and most likely answer to this crossword clue is the 8 letter word RESCINDS
I've seen this crossword clue in The Guardian
R
E
S
C
I
N
D
S
More clues leading to the result RESCINDS
Buddy explains!

The straight part
We know that "Cancels" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cancels = rescinds.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 RESCINDS mean?
RESCINDS verb- To repeal, annul, or declare void; to take (something such as a rule or contract) out of effect.
- To cut away or off.