Old rebel who initiates drugs bust in a hospital? (6)
I believe the answer is:
anarch
'old rebel who initiates' is the definition.
'anarch' can be an answer for 'old rebel' (historical term for an anarchist). I am not certain of the remainder of the definition.
'drugs bust in a hospital?' is the wordplay.
'drugs bust' becomes 'narc' (I am not sure about this - if you are sure you should believe this answer much more).
'in' means one lot of letters goes inside another.
'hospital?' becomes 'h' (abbreviation for hospital on maps).
'a'+'h'='ah'
'narc' inserted within 'ah' is 'ANARCH'.
(Another definition for anarch that I've seen is " Revolutionary".)