Otherwise a noted school of economics (4)
I believe the answer is:
else
'otherwise' is the definition.
(synonyms)
'a noted school of economics' is the wordplay.
I cannot really understand how this works, but
'school' could be 'lse' (London School of Economics) and 'lse' is present in the answer.
A single letter 'e' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for else that I've seen before include "Eels (anag)" , "Other than (what is under consideration)" , "As an alternative" , "Otherwise; different from" , "Besides, otherwise" .)