Dictates new exam involving litmus paper (4,4)

I believe the answer is:

acid test

I'm a little stuck... Click here to teach me more about this clue!

'exam involving litmus paper' is the definition.
I can't judge whether this definition defines the answer.

'dictates new' is the wordplay.
'new' indicates an anagram.
'dictates' anagrammed gives 'ACID TEST'.

Can you help me to learn more?

(Other definitions for acid test that I've seen before include "A severe or conclusive exam or trial" , "crucial experiment" , "that one should run for gold?" , "Dictates to undergo conclusive trial" , "Severe trial; old assay method" .)

I've seen this clue in The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.