Apprentice, learner (7)
I believe the answer is:
trainee
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">apprentice</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(someone undergoing training)</span><br/ ><br/ >'<span class="explanation-format__original">learner</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(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" .)