In test, four are found to be unimportant (7)
I believe the answer is:
trivial
'be unimportant' is the definition.
(similar in meaning)
'in test four' is the wordplay.
'in' is an insertion indicator.
'test' becomes 'trial' (synonyms).
'four' becomes 'IV' (roman numeral).
'trial' placed around 'iv' is 'TRIVIAL'.
'are found to' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for trivial that I've seen before include "Inconsequential, too minor to be bothered about" , "lacking weight" , "Rinky-dink" , "Insignificant" , "Of little value" .)