Listen in to nurse (6)
I believe the answer is:
attend
This clue is a double definition.
'listen' is the first definition.
(attending is a kind of listening)
'to nurse' is the second definition.
(thesaurus)
'in' is the link.
(Other definitions for attend that I've seen before include "put in an appearance" , "Be present or appear at" , "Listen closely" , "minister" , "Completed" .)