Nurse in Moorfields is terrific (6)
I believe the answer is:
sister
'nurse' is the definition.
(I've seen this before)
'in moorfields is terrific' is the wordplay.
'in' says the answer is hidden in the clue.
'SISTER' is hidden in the letters of 'moorfields is terrific'.
(Other definitions for sister that I've seen before include "Member of family" , "Resist about the sibling" , "Nun's title" , "of the same origin" , "A relative to resist" .)