The most common and most likely answer to this crossword clue is the 5 plus 3 plus 5 letter word TRIAL AND ERROR
I've seen this crossword clue in The Guardian
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More clues leading to the result TRIAL AND ERROR
- Dread holding broadcast back with light experimentation
- Method of solving a problem in heart of Africa — a land in panic
- Practical method riled narrator, struggling
- Fear surrounding money and experimental methodology
- Method of solving problems in revolutionary manner with country in panic
- Experimental method riled narrator absurdly
- Experimentation may bring fear across Rhode Island
- Fear about lard in a cooking method to achieve a solution
- Experimental justification for the Court of Appeal?
- Hit or miss affair resulting in wrongful conviction?
Buddy explains!

The straight part
We know that "experimental methodology" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case experimental methodology = trial and error.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.