Sober people hosting party — mum's in a state (7)
I believe the answer is:
alabama
'sober people hosting party mum's in a state' is the definition.
I can't tell whether this definition defines the answer.
'hosting party mum's in a state' is the wordplay.
'hosting' is an insertion indicator (inserted letters are welcomed in or hosted).
'party' becomes 'lab' (abbreviation for Labour).
'mum's in' becomes 'a' (I can't justify this - if you can you should give a lot more credence to this answer).
'state' becomes 'ma' (abbreviation for Massachusetts).
'a'+'a'='aa'
'lab' put inside 'aa' is 'alaba'.
'alaba'+'ma'='ALABAMA'
Can you help me to learn more?
(Other definitions for alabama that I've seen before include "part of US" , "where cotton can be produced" , "US state on the Gulf of Mexico" , "US state west of Georgia" , "US state in which Birmingham is situated" .)