Rash letters excised from case history put together for association (7)
I believe the answer is:
society
'for association' is the definition.
(society is a kind of association)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for society that I've seen before include "Fellowship, association" , "An organised community, may be high" , "Social group" , "Fellowship; company" , "Fellowship; fashionable world" .)