Different rate set around institute for formal written work (8)
I believe the answer is:
treatise
'formal written work' is the definition.
(I've seen this before)
'different rate set around institute' is the wordplay.
'different' indicates an anagram (letters placed in a different order).
'around' is an insertion indicator.
'institute' becomes 'i' (common abbreviation as in MIT).
'rate'+'set'='rateset'
'rateset' is an anagram of 'treatse'.
'treatse' enclosing 'i' is 'TREATISE'.
'for' is the link.
(Other definitions for treatise that I've seen before include "formal document" , "Iterates in dissertation" , "Disquisition" , "A written work about treaties" , "Essay on theme" .)