Clue: Retiring nurses fighting authority, provider of shoddy work (6)
Answer: COWBOY
Explanation: Definition: provider of shoddy work
 COY(retiring/shy or pretending to be shy) **containing**(nurses) WBO(abbrev. for the World Boxing Organisation, one of the authorities sanctioning professional boxing fights).
Defn: A service provider who is dishonest, careless, or unqualified, producing shoddy work.