The most common and most likely answer to this crossword clue is the 7 letter word ATTESTS
I've seen this crossword clue in The Daily Telegraph
A
T
T
E
S
T
S
More clues leading to the result ATTESTS
- Signs up old serving women receiving trial
- Certifies whereabouts of Barmy Army?
- Declares at cricket matches
- Gives evidence at trials
- Confirms visiting cricket matches
- Confirms as attending internationals
- Swears at cricket matches
- Demonstrates outside Lord’s and Edgbaston, say?
- Witnesses for trial sat nervously about
Buddy explains!

The straight part
We know that "Swears" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case swears = attests.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 ATTESTS mean?
ATTESTS verb- To affirm to be correct, true, or genuine.
- To certify by signature or oath.
- To certify in an official capacity.
- To supply or be evidence of.
- To put under oath.
- To call to witness; to invoke.