Record of police department sent back to arrest son (4)
I believe the answer is:
disc
'record' is the definition.
(synonyms)
'police department sent back to arrest son' is the wordplay.
'police department' becomes 'cid' (I've seen this in other clues).
'sent back' shows that the letters should be reversed in order.
'to arrest' is an insertion indicator.
'son' becomes 's'.
'cid' written backwards gives 'dic'.
'dic' placed around 's' is 'DISC'.
'of' acts as a link.
(Other definitions for disc that I've seen before include "Capital of India" , "jockey may be after" , "counter" , "Thin flat circular object" , "Layer of cartilage between spinal vertebrae" .)