University engaged in class meeting (5)
I believe the answer is:
forum
'meeting' is the definition.
(forum is a kind of meeting)
'university engaged in class' is the wordplay.
'university' becomes 'u'.
'engaged in' indicates putting letters inside.
'class' becomes 'form' (form class is a kind of class).
'u' inserted into 'form' is 'FORUM'.
(Other definitions for forum that I've seen before include "Ancient Roman marketplace or place for public discussions" , "Place for open discussion" , "Place where public discussion is held, as in ancient Rome" , "Place where public meeting or discussion is held" , "Public meeting-place for open discussion" .)