Grand house excludes liberal section of society (5)
I believe the answer is:
caste
'society' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for caste that I've seen before include "Social division in India" , "Social class in Hinduism" , "Brahmans for instance" , "Social station" , "Group within society" .)