Aim to teach (5)
I believe the answer is:
train
This clue is a double definition.
'aim' is the first definition.
(synonyms)
'teach' is the second definition.
(I know that train is a more specific form of teach)
'to' is the link.
(Other definitions for train that I've seen before include "Work out" , "Long back section of a gown that's drawn along the floor" , "Public transport on the railway" , "See 19" , "Aim < to prepare < railway carriages" .)