Debauched regent, as rank (8)
I believe the answer is:
sergeant
'rank' is the definition.
(I've seen this before)
'debauched regent as' is the wordplay.
'debauched' indicates an anagram.
'regent'+'as'='regentas'
'regentas' is an anagram of 'SERGEANT'.
(Other definitions for sergeant that I've seen before include "Rank above corporal" , "Noncommissioned military officer" , "Troy" , "Police rank" , "CARRY ON FILM" .)