No-nonsense detective abandoning precinct (6)
I believe the answer is:
strict
'no-nonsense' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for strict that I've seen before include "Allowing no laxness" , "Rigidly enforced" , "Allowing no deviation from a standard" , "Observing exact rules" , "Stringent" .)