Centre of learning with action applied to students' club (5)
I believe the answer is:
union
'club' is the definition.
(workers' club)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for union that I've seen before include "mating" , "(Pipe) coupling" , "Workers' organisation or marriage" , "Jack may join when on the staff" , "Merger like marriage" .)