As opposed to Windsor or Harrow (4)
I believe the answer is:
eton
'harrow' is the definition.
(I've seen this in another clue)
'as opposed to windsor' is the wordplay.
I cannot really see how this works, but
'to' is present in the answer.
The remaining letters 'en' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'or' acts as a link.
Can you help me to learn more?
(Other definitions for eton that I've seen before include "Place for learning" , "Public school (sounds like 20)" , "collar, perhaps?" , "Famous English public school" , "learn here?" .)