Joins educational institution before setback (6)
I believe the answer is:
unites
'joins' is the definition.
(uniting is a kind of joining)
'educational institution before setback' is the wordplay.
'educational institution' becomes 'uni' (short for university).
'before' says to put letters next to each other.
'setback' becomes 'tes' (I've seen this in other clues).
'uni'+'tes'='UNITES'
(Other definitions for unites that I've seen before include "Merges" , "Marries" , "Brings together, allies" , "Becomes one" , "Comes together as one" .)