Domains ruled by king or queen (6)
I believe the answer is:
realms
'domains ruled by king or queen' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for realms that I've seen before include "Domains - provinces" , "Kingdoms, domains" , "Kingdoms, or fields of activity" , "Fields of activity or interest - sound monarchical" , "areas of interest" .)