Possible Clues:

• Sharp middleman contacts police department in the middle of homicide
• The current one, Diane, takes a C-sharp
• Detectives in US agency retired, remaining sharp
• So sour a bunch of detectives to listen to, I see
• Sharp reverse for intelligence agency involving endless risk
• Like lemons
• Account of detective cavorting with one with sharp taste
• Being sour to the taste
• Detectives in US agency, retired but sharp
• Short account in which African dictator appears to be bitter