Instruct apprentice, initially in college (5)
I believe the answer is:
teach
'instruct' is the definition.
(I've seen this before)
'apprentice initially in college' is the wordplay.
'apprentice initially' becomes 'a' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'college' becomes 'tech' (I've seen this before).
'a' inserted inside 'tech' is 'TEACH'.
(Other definitions for teach that I've seen before include "Give instruction to" , "Tutor" , "train" , "Instruct, enlighten" , "Coach" .)