Banter about involvement with drugs (8)
I believe the answer is:
repartee
'banter' is the definition.
(both can mean jocular conversation)
'about involvement with drugs' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'involvement' becomes 'part' (part is a kind of involvement).
'with drugs' becomes 'ee' (an abbreviation for ecstasy written twice. I am not sure about the 'with' bit.).
're'+'part'+'ee'='REPARTEE'
Can you help me to learn more?
(Other definitions for repartee that I've seen before include "Badinage" , "Banter - pear tree (anag)" , "comeback" , "Witty exchange" , "Clever chat" .)