Society relaxed about summit where dodgy booze was served (9)
I believe the answer is:
speakeasy
'where dodgy booze was served' is the definition.
(illegal bar in US in the prohibition era)
'society relaxed about summit' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'relaxed' becomes 'easy' (associated in meaning).
'about' is a charade indicator (letters next to each other).
'summit' becomes 'peak' (synonyms).
'easy' after 'peak' is 'peakeasy'.
's'+'peakeasy'='SPEAKEASY'
(Other definitions for speakeasy that I've seen before include "Illicit bar during Prohibition" , "Dive" , "Illicit drinking club (US)" , "Illicit club during Prohibition" , "Prohibition watering hole" .)