Show liberal his awful ruin (8)
I believe the answer is:
demolish
'ruin' is the definition.
(thesaurus)
'show liberal his awful' is the wordplay.
'show' becomes 'demo' (I've seen this before).
'liberal' becomes 'l' (abbreviation).
'awful' is an anagram indicator.
'his' with letters rearranged gives 'ish'.
'demo'+'l'+'ish'='DEMOLISH'
(Other definitions for demolish that I've seen before include "Break down" , "Raze to the ground" , "Knock down, say a building" , "Knock down, a building or argument perhaps" , "Destroy completely" .)