The most common and most likely answer to this crossword clue is the 8 letter word ASSERTED
I've seen this crossword clue in The Daily Telegraph
A
S
S
E
R
T
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D
More clues leading to the result ASSERTED
Buddy explains!
The straight part
We know that "Insisted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case insisted = asserted.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 ASSERTED mean?
ASSERTED 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.
- Stated, declared or alleged, especially with confidence but no proof