Mentor (7)
'mentor' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for adviser that I've seen before include "ID saver (anag.)" , "Guide" , "Counseller" , "Counsellor, mentor" , "subject's specialist consultant" .)
'mentor' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for teacher that I've seen before include "Coach" , "Mentor" , "supply?" , "CARRY ON FILM" , "Cheater (anag.)" .)