Bust — or the opposite overwhelming society (5)
I believe the answer is:
bosom
'bust' is the definition.
(I've seen this in another clue)
'the opposite overwhelming society' is the wordplay.
'the opposite' becomes 'boom' (I can't justify this - if you can you should believe this answer much more).
'overwhelming' means one lot of letters goes inside another.
'society' becomes 's' (common abbreviation in names of organisations).
'boom' placed around 's' is 'BOSOM'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for bosom that I've seen before include "Embrace" , "A close affectionate and protective acceptance" , "Intimate" , "(Female's) chest" , "Woman's chest" .)