Job facing a student of letters (6)
I believe the answer is:
postal
'of letters' is the definition.
'job facing a student' is the wordplay.
'job' becomes 'post' (post is a kind of job**).
'facing' says to put letters next to each other.
'student' becomes 'l' (as in L-plates for learner drivers).
'post'+'a'+'l'='POSTAL'
(Other definitions for postal that I've seen before include "to go so mad in America" , "Relating to mail delivery" , "Relating to mail service" , "Sort of vote" , "Type of order" .)