Decisive check that may produce basic result? (6,4)
I believe the answer is:
litmus test
'may produce basic result?' is the definition.
I can't judge whether this definition defines the answer.
'decisive check' is the wordplay.
'decisive' becomes 'litmus' (I can't explain this - if you can you should believe this answer much more).
'check' becomes 'test' (as in testing or checking something works).
'litmus'+'test'='LITMUS TEST'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for litmus test that I've seen before include "Chemical trial" , "Observer may see red after one" .)