Dungeons later vandalised, one looking down in the mouth? (6,7)
I believe the answer is:
dental surgeon
'one looking down in the mouth?' is the definition.
(a dental surgeon operates on the mouth)
'dungeons later vandalised' is the wordplay.
'vandalised' is an anagram indicator.
'dungeons'+'later'='dungeonslater'
'dungeonslater' is an anagram of 'DENTAL SURGEON'.
(Other definitions for dental surgeon that I've seen before include "One treating teeth" , "One qualified to drill" , "Canine expert" , "operator on bridge?" , "Medic having to fill in" .)