Murdered in the crime around Los Angeles (5)
'murdered' is the definition.
('slay' can be a synonym of 'murder')
'crime around los angeles' is the wordplay.
'crime' becomes 'sin'.
'around' means one lot of letters goes inside another.
'los angeles' becomes 'la'.
'sin' placed around 'la' is 'SLAIN'.
'in the' acts as a link.
(Other definitions for slain that I've seen before include "Violently killed", "Put to the sword", "Killed, murdered", "Slaughtered".)