College reunion attendees
I believe the answer is:
alumni
'college reunion attendees' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alumni that I've seen before include "Put too much strain on, as Revenue Commissioners do" , "we studied at a certain place" , "Former (school) pupils" , "Past pupils, former students" , "Schoolkids once" .)