Go over city crime arrests (5)
I believe the answer is:
recap
'go over' is the definition.
(I've seen this before)
'city crime arrests' is the wordplay.
'city' becomes 'EC' (the City of London postcode).
'crime' becomes 'rap' (I am not sure about this - if you are sure you should believe this answer much more).
'arrests' is an insertion indicator (inserted letters are held or arrested).
'ec' put within 'rap' is 'RECAP'.
Can you help me to learn more?
(Other definitions for recap that I've seen before include "Summarise, run over" , "cover the same ground again" , "Go over the main points again, in short" , "Go over old ground" , "Retrospective summary" .)