Shame of police officer vacuously slandering ethnic group (8)
I believe the answer is:
disgrace
'shame' is the definition.
(I know this)
'police officer vacuously slandering ethnic group' is the wordplay.
'police officer' becomes 'DI' (abbreviation for Detective Inspector).
'vacuously' means to remove the middle letters.
'ethnic group' becomes 'race' (a racial group).
'slandering' with its centre removed is 'sg'.
'di'+'sg'+'race'='DISGRACE'
'of' is the link.
(Other definitions for disgrace that I've seen before include "Loss of reputation as the result of dishonourable action" , "Cause of shame or dishonour" , "Bring shame upon" , "Shame or loss of respect" , "Loss of good reputation" .)