Apprentice, learner (7)
I believe the answer is:
trainee
I believe this is a double definition.
'apprentice' is the first definition.
(someone undergoing training)
'learner' is the second definition.
(I've seen this before)
(Other definitions for trainee that I've seen before include "New recruit" , "Person being instructed in work" , "One undergoing instruction" , "one not yet qualified" , "One being taught a job" .)