Drugs that man from Bow smuggled inside flipping kid (4)
I believe the answer is:
gear
'drugs' is the definition.
(gear can informally mean illegal drugs)
'man from bow smuggled inside flipping kid' is the wordplay.
'man from bow' becomes 'e' (I am not sure about this - if you are sure you should believe this answer much more).
'smuggled inside' is an insertion indicator.
'flipping' says the letters should be written backwards.
'kid' becomes 'rag' (I've seen this in other clues).
'rag' in reverse letter order is 'gar'.
'e' placed inside 'gar' is 'GEAR'.
'that' is the link.
(Other definitions for gear that I've seen before include "Trendy clothes - changed in car?" , "often changed when driving" , "Equipment; dress" , "illegal drugs" , "Illicit drugs (slang) - kit" .)