Violent pub full of old swine (4,4)
I believe the answer is:
wild boar
'swine' is the definition.
(wild boar is a kind of swine)
'violent pub full of old' is the wordplay.
'violent' becomes 'wild' ('wild' can be a synonym of 'violent'**).
'pub' becomes 'bar' (I've seen this before).
'full of' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'bar' going around 'o' is 'boar'.
'wild'+'boar'='WILD BOAR'
(Other definitions for wild boar that I've seen before include "Untamed pig" , "Feral pig" , "Non-domesticated pig" , "strong meat" , "Game" .)