Corruption - Department’s a very pit, outrageous (9)
I believe the answer is:
depravity
'corruption' is the definition.
(synonyms)
'department's a very pit outrageous' is the wordplay.
'department' becomes 'd' (abbreviation eg in MOD Ministry of Defence).
'outrageous' indicates an anagram (an outrageous spelling).
'a'+'very'+'pit'='averypit'
'averypit' with letters rearranged gives 'epravity'.
'd'+'epravity'='DEPRAVITY'
(Other definitions for depravity that I've seen before include "Moral corruption" , "Moral turpitude" , "Immoral act(s) - wickedness" .)