Tries to disrupt genuine trial (9)
I believe the answer is:
rehearsal
'trial' is the definition.
(I've seen this before)
'tries to disrupt genuine' is the wordplay.
'tries' becomes 'hears' ('hear' can be a synonym of 'try').
'to disrupt' indicates putting letters inside.
'genuine' becomes 'real' ('real' is associated in meaning with 'genuine').
'hears' placed within 'real' is 'REHEARSAL'.
(Other definitions for rehearsal that I've seen before include "Dramatic practice" , "Preparation for a show" , "Dry run" , "Practice - run-through" , "Practice in theatre etc" .)