Lady dines sloppily, showing gluttony perhaps (6,3)
I believe the answer is:
deadly sin
'gluttony perhaps' is the definition.
(gluttony is a kind of deadly sin)
'lady dines sloppily' is the wordplay.
'sloppily' indicates an anagram (I've seen this in other clues).
'lady'+'dines'='ladydines'
'ladydines' is an anagram of 'DEADLY SIN'.
'showing' acts as a link.
(Other definitions for deadly sin that I've seen before include "envy for example" , "Anger, covetousness, envy, gluttony, lust, pride or sloth" , "Greed, perhaps" , "Eg, lust or gluttony" , "a cause of damnation" .)