Listens during actual show trial? (9)
I believe the answer is:
rehearsal
'show trial?' is the definition.
(I've seen this before)
'listens during actual' is the wordplay.
'listens' becomes 'hears' (I've seen this before).
'during' is an insertion indicator.
'actual' becomes 'real' ('real' can be a synonym of 'actual').
'hears' going within 'real' is 'REHEARSAL'.
(Other definitions for rehearsal that I've seen before include "Dry run" , "Practice session in preparation for public performance" , "Practice - run-through" , "preparation in house?" , "show trial" .)