Detectives chasing dashed off (6)
I believe the answer is:
rancid
'off' is the definition.
(I've seen this before)
'detectives chasing dashed' is the wordplay.
'detectives' becomes 'CID' (abbreviation for Criminal Investigation Department).
'chasing' means one lot of letters go next to another.
'dashed' becomes 'ran' (I've seen this in another clue).
'cid' after 'ran' is 'RANCID'.
(Other definitions for rancid that I've seen before include "Sour, rotting" , "Tasting or smelling sour, butter say" , "Rank-smelling." , "Turned - foul-smelling" , "Sour like stale grease 96)" .)