The most common and most likely answer to this crossword clue is the 7 letter word ASSERTS
I've seen this crossword clue in The Guardian
A
S
S
E
R
T
S
Buddy explains!

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 ASSERTS mean?
ASSERTS verb- To declare with assurance or plainly and strongly; to state positively.
- To use or exercise and thereby prove the existence of.
- To maintain or defend, as a cause or a claim, by words or measures; to vindicate a claim or title to
- To specify that a condition or expression is true at a certain point in the code.
- To set a signal on a line using a voltage or electric current.