Beastly sound a pub outside is responsible for (7)
I believe the answer is:
inhuman
'beastly' is the definition.
(as opposed to human)
'sound a pub outside is responsible for' is the wordplay.
'sound' indicates a 'sounds like' (homophone) clue.
'a pub' becomes 'inn' (an inn is a type of pub).
'outside' says to put letters next to each other (outside can mean adjacent to).
'is responsible for' becomes 'human' (I can't justify this - if you can you should believe this answer much more).
'inn' is a homophone of 'in'.
'in'+'human'='INHUMAN'
Can you help me to learn more?
(Other definitions for inhuman that I've seen before include "barbarous and brutal" , "diabolical ..." , "Beastly" , "Callously cruel" , "Cruel, bestial" .)