Left a student at the entrance (6)
I believe the answer is:
portal
'the entrance' is the definition.
(portal is a kind of entrance)
'left a student' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'student' becomes 'l' (as in L-plates for learner drivers**).
'port'+'a'+'l'='PORTAL'
'at' acts as a link.
(Other definitions for portal that I've seen before include "Grand and imposing entrance" , "Special website bringing together information from diverse sources in a uniform way" , "An imposing gateway" , "An imposing gate or doorway" , "Gate, entrance" .)