Noah Webster's alma mater (4)
I believe the answer is:
'noah webster's alma mater' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yale that I've seen before include "US Ivy League college" , "American university or kind of lock" , "Famous American university in Connecticut" , "Heraldic animal" , "Mass. university" .)