Nurse translated mysterious characters (5)
I believe the answer is:
runes
'mysterious characters' is the definition.
(I've seen this in another clue)
'nurse translated' is the wordplay.
'translated' indicates an anagram.
'nurse' is an anagram of 'RUNES'.
(Other definitions for runes that I've seen before include "Old letters" , "marks on old tablets" , "Mysterious letters" , "Small stones bearing symbols with magic significance" , "old characters" .)