Practice, rehearsal (5,3)
I believe the answer is:
dummy run
I believe this clue is a double definition.
'practice' is the first definition.
(I've seen this before)
'rehearsal' is the second definition.
(a dummy run is a practice or rehearsal)
(Other definitions for dummy run that I've seen before include "A try-out or test" , "Practice session" , "Rehearsal" , "Practice, trial" .)