Join university side, leaving in the morning (5)
I believe the answer is:
unite
'join' is the definition.
('unite' can be a synonym of 'join')
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for unite that I've seen before include "Club together" , "Make one" , "Come, or join together" , "Link" , "Amalgamate" .)