A bit of poetry is depraved (8)
I believe the answer is:
perverse
'is depraved' is the definition.
(thesaurus)
'a bit of poetry' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'bit of poetry' becomes 'verse' (verse means poetry).
'per'+'verse'='PERVERSE'
(Other definitions for perverse that I've seen before include "'Unreasonable, awkward (8)'" , "Irregular" , "Obstinately wrong-headed" , "Cross-grained" , "'Contrary to what's considered right, proper or good (8)'" .)