Where the pupils get bigger, of course (6)
I believe the answer is:
school
This might be a double definition.
'where the pupils' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'bigger of course' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'get' acts as a link.
Can you help me to learn more?
(Other definitions for school that I've seen before include "company that's all at sea" , "a lot of swimmers" , "building" , "training centre" , "College" .)