Put a stop to almost everything trivial (5)
I believe the answer is:
banal
'trivial' is the definition.
('banal' can be a synonym of 'trivial')
'put a stop to almost everything' is the wordplay.
'put a stop to' becomes 'ban'.
'almost' means to remove the last letter (most of the word but not all of it).
'everything' becomes 'all' (I've seen this before).
'all' with its final letter taken off is 'al'.
'ban'+'al'='BANAL'
(Other definitions for banal that I've seen before include "Uninteresting, commonplace" , "Obvious and boring" , "Pedestrian" , "Overfamiliar through overuse" , "tired" .)