Doctor resists nurses (7)
I believe the answer is:
sisters
'nurses' is the definition.
(female nurses are often addressed as sister)
'doctor resists' is the wordplay.
'doctor' is an anagram indicator.
'resists' with letters rearranged gives 'SISTERS'.
(Other definitions for sisters that I've seen before include "Relatives in hospital?" , "Nuns' titles" , "Female siblings" , "Family relatives" , "Nuns - nurses - siblings" .)