Regions unite concerning charity (6)
I believe the answer is:
realms
'regions' is the definition.
(I've seen this in another clue)
'concerning charity' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'charity' becomes 'alms' (alms is a kind of charity).
're'+'alms'='REALMS'
'unite' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for realms that I've seen before include "Fields of activity or interest - sound monarchical" , "Kingdoms, or fields of activity" , "areas of interest" , "Domains - provinces" , "regions" .)