Sister translates runes (5)
I believe the answer is:
nurse
'sister' is the definition.
(I've seen this before)
'translates runes' is the wordplay.
'translates' is an anagram indicator (I've seen 'translated' mean this).
'runes' anagrammed gives 'NURSE'.
(Other definitions for nurse that I've seen before include "Qualified carer" , "One skilled in caring for the sick" , "Angel of mercy" , "Trained carer" , "Entangle" .)