Train maker of shoes in different sizes (6)
I believe the answer is:
school
'train' is the definition.
(both can mean to teach or coach)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for school that I've seen before include "Teach - fishes swimming" , "Where 2 takes place" , "Group of artists < in coach" , "A number of fish" , "Group of sea creatures" .)