Match on after college (5)
I believe the answer is:
union
'match' is the definition.
(I've seen this before)
'on after college' is the wordplay.
'after' says to put letters next to each other.
'college' becomes 'uni' (short for university).
'on' after 'uni' is 'UNION'.
(Other definitions for union that I've seen before include "Togetherness" , "Workers' group" , "pearl amongst Shakespeareans" , "Coalescence, join as one" , "Coupling, merger" .)