The most common and most likely answer to this crossword clue is the 6 letter word ATTEST
I've seen this crossword clue in The Times
A
T
T
E
S
T
More clues leading to the result ATTEST
- Provide evidence for a tutor’s first examination
- Confirm you might find cricket lover here?
- Confirm where international cricket fan might be?
- Demonstrate during an Ashes match?
- Certify where cricket enthusiasts may be?
- A trial involving one leading tense witness
- Witness attending trial
- Ratify part of Ashes crowd?
- Evidence when watching big game in person?
- Swear to cutting a quarter of food, having put most on?
Buddy explains!

The straight part
We know that "Confirm" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case confirm = attest.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 ATTEST mean?
ATTEST 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.