College takes on alliance (5)
I believe the answer is:
union
'alliance' is the definition.
(I've seen this before)
'college takes on' is the wordplay.
'college' becomes 'uni' (short for university).
'takes' means one lot of letters go next to another.
'uni'+'on'='UNION'
(Other definitions for union that I've seen before include "Jack may join when on the staff" , "The joining of two or more together" , "A joining together as in marriage" , "Association with a common purpose" , "America" .)