Old clown, I blunder into drugs? (7)
I believe the answer is:
pierrot
'old clown' is the definition.
'pierrot' can be an answer for 'clown' (I've seen this before). I'm not certain of the 'old' bit.
'i blunder into drugs?' is the wordplay.
'blunder' becomes 'err' (I've seen this before).
'into' means one lot of letters goes inside another.
'drugs?' becomes 'pot' (slang term for mariujana).
'i'+'err'='ierr'
'ierr' inserted into 'pot' is 'PIERROT'.
Can you help me to learn more?
(Other definitions for pierrot that I've seen before include "French stage character with white face and costume" , "Sad white-faced clown" , "Period; incantation" , "Male clown from French pantomime" , "I report on French pantomime clown" .)