Listens during actual dummy run (9)
I believe the answer is:
rehearsal
'dummy run' is the definition.
(I've seen this before)
'listens during actual' is the wordplay.
'listens' becomes 'hears' (I've seen this before).
'during' indicates putting letters inside.
'actual' becomes 'real' ('real' can be a synonym of 'actual').
'hears' put into 'real' is 'REHEARSAL'.
(Other definitions for rehearsal that I've seen before include "Preparation for a show" , "Dummy run" , "show trial" , "Play run-through" , "Practice - run-through" .)