Arrange lecture about conclusion of murder case (11)
I believe the answer is:
orchestrate
'arrange' is the definition.
(I've seen this before)
'lecture about conclusion of murder case' is the wordplay.
'lecture' becomes 'orate' (I've seen this before).
'about' indicates putting letters inside.
'conclusion of' says to take the final letters.
'case' becomes 'chest' (both are types of container).
The last letter of 'murder' is 'r'.
'r'+'chest'='rchest'
'orate' going around 'rchest' is 'ORCHESTRATE'.
(Other definitions for orchestrate that I've seen before include "Arrange for a full band" , "Compose" , "Organise (music)" , "Organise (a complex enterprise)" , "Score (a piece)" .)