Sniffs drugs on the job working on a lead in the law enforcement business (6,3)
I believe the answer is:
police dog
'sniffs drugs on the job working on a lead' is the definition.
I can't tell whether this defines the answer.
'law enforcement business' is the wordplay.
'law' becomes 'police' ('police' can be a synonym of 'law').
'enforcement business' becomes 'dog' (I can't justify this - if you can you should believe this answer much more).
'police'+'dog'='POLICE DOG'
'in the' is the link.
Can you help me to learn more?
(Other definitions for police dog that I've seen before include "Drug hunter" , "one taking lead in war on crime" , "Working animal" , "maybe I do a lot of sniffing" , "Canine for the boys in blue" .)