Nun from the slums is Teresa (6)
I believe the answer is:
sister
'nun' is the definition.
(Sister is an example)
'from the slums is teresa' is the wordplay.
'from' indicates a hidden word.
'SISTER' can be found hidden inside 'slums is teresa'.
(Other definitions for sister that I've seen before include "Close relation" , "habits' - one who has them" , "of the same origin" , "Nun's title" , "Nurse, nun and sibling" .)