Burdening trial's opening with questioning (7)
I believe the answer is:
tasking
'burdening' is the definition.
(burdening someone with a task)
'trial's opening with questioning' is the wordplay.
'opening' says to take the initial letters.
'with' means one lot of letters go next to another.
'questioning' becomes 'asking' (I've seen this before).
The first letter of 'trials' is 't'.
't'+'asking'='TASKING'
(Other definitions for tasking that I've seen before include "piecework" , "Making great demands" .)