Working empty parable into sermon (9)
I believe the answer is:
operation
'working' is the definition.
(how something operates)
'empty parable into sermon' is the wordplay.
'empty' means to remove the middle letters.
'into' indicates putting letters inside.
'sermon' becomes 'oration' (both can mean a speech).
'parable' with its middle removed is 'pe'.
'pe' inserted inside 'oration' is 'OPERATION'.
(Other definitions for operation that I've seen before include "activity" , "In hospital procedure" , "Handling" , "Surgical or military procedure" , "medical treatment" .)