The homicide department (3)

I believe the answer is:

cid

I'm a little stuck... Click here to teach me more about this clue!

'the homicide department' is the definition.
The definition suggests a singular noun which matches the answer.

'homicide department' is the wordplay.
'homicide' becomes 'ci' (I am not sure about this - if you are sure you should believe this answer much more).
'department' becomes 'd' (abbreviation eg in MOD Ministry of Defence).
'ci'+'d'='CID'

Can you help me to learn more?

Want a hint initially instead of a full solution? Install my app