Doctor instructs dire visiting health worker (8,5)
I believe the answer is:
district nurse
'visiting health worker' is the definition.
'doctor instructs dire' is the wordplay.
'doctor' indicates an anagram.
'instructs'+'dire'='instructsdire'
'instructsdire' anagrammed gives 'DISTRICT NURSE'.
(Other definitions for district nurse that I've seen before include "NHS visitor" , "Itinerant local health worker" , "care provider" , "Local medical worker" , "One tending patients in their homes" .)