Place to learn about harmony (5)
I believe the answer is:
union
'harmony' is the definition.
(thesaurus)
'place to learn about' is the wordplay.
'place to learn' becomes 'uni'.
'about' becomes 'on'.
'uni'+'on'='UNION'
(Other definitions for union that I've seen before include "Jack may join when on the staff" , "junction" , "Workers' association - marriage" , "Amalgam" , "Association - guild" .)