College, from middle of fifteenth century (4)
I believe the answer is:
eton
'college' is the definition.
(I've seen this before)
'middle of fifteenth century' is the wordplay.
'middle of' means to look at the middle letters.
'century' becomes 'ton' (both can mean one hundred of something).
The middle letter of 'fifteenth' is 'e'.
'e'+'ton'='ETON'
'from' acts as a link.
(Other definitions for eton that I've seen before include "Independent school" , "School near Slough" , "School; jacket type" , "collar, perhaps?" , "Public school (sounds like 20)" .)