Not moving right, interrupting a trial (2,4)
I believe the answer is:
at rest
'not moving' is the definition.
(I've seen this in another clue)
'right interrupting a trial' is the wordplay.
'right' becomes 'r' (common abbreviation).
'interrupting' indicates putting letters inside.
'trial' becomes 'test' (synonyms).
'a'+'test'='atest'
'r' inserted into 'atest' is 'AT REST'.
(Other definitions for at rest that I've seen before include "Free from trouble or anxiety" , "Motionless" , "Still" , "Not moving, free from trouble - maybe dead" , "In relaxed state, perhaps dead" .)