Obsessive hobbyist is a teacher at Hogwarts? (12)
I believe the answer is:
trainspotter
'obsessive hobbyist' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'a teacher at hogwarts?' is the wordplay.
I cannot really understand how this works, but
'a' is found in the answer.
'at' could be 'in' (synonymous in some cases - eg at school, in school) and 'in' is present in the answer.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for trainspotter that I've seen before include "One interested in engines" , "anorak" , "Boring person" , "Nerd" , "Gricer" .)