Rulers required in college? (5)
I believe the answer is:
kings
This might be a double definition.
'rulers' is the first definition.
(king is a kind of ruler)
'in college?' is the second definition.
'King's' can be an answer for 'college?' (King's College London). I am not sure about the 'in' bit.
'required' is the link.
Can you help me to learn more?
(Other definitions for kings that I've seen before include "College etc of royal foundation" , "Valley of the - -" , "Two-part book" , "feature of 21/23 [NATIVITY SCENE]" , "Name of two Old Testament books" .)