Insignificant stuff - I bottle it in test (10)
I believe the answer is:
triviality
'insignificant stuff' is the definition.
(stuff which is trivial)
'i bottle it in test' is the wordplay.
'bottle' becomes 'vial' (vial is a kind of bottle).
'in' indicates putting letters inside.
'test' becomes 'try' (synonyms).
'i'+'vial'+'it'='ivialit'
'ivialit' inserted within 'try' is 'TRIVIALITY'.
(Other definitions for triviality that I've seen before include "Unimportance" , "Insignificance" , "Trifling item" .)