Boundary of either kind in test is commonplace (7)
I believe the answer is:
trivial
'is commonplace' is the definition.
(synonyms)
'boundary of either kind in test' is the wordplay.
I cannot really see how this works, but
'boundary' could be 'vi' (type of boundary in cricket, roman numerals) and 'vi' is present in the answer.
'test' could be 'trial' (synonyms) and 'trial' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for trivial that I've seen before include "lacking weight" , "Petty, piffling" , "Piddling" , "Meaningless" , "not significant" .)