Drugs ultimately wanton king rolled in joint (4)
I believe the answer is:
knee
'joint' is the definition.
(I know that knee is a type of joint)
'drugs ultimately wanton king rolled' is the wordplay.
'drugs' becomes 'ee' (an abbreviation for ecstasy written twice).
'ultimately' indicates one should take the final letters.
'king' becomes 'K' (abbreviation for king in chess).
'rolled' says the letters should be written in reverse (letters roll back).
The last letter of 'wanton' is 'n'.
'ee'+'n'+'k'='eenk'
'eenk' written backwards gives 'KNEE'.
'in' is the link.
(Other definitions for knee that I've seen before include "one is bent on submission" , "Hinged joint" , "Hinge between the thigh and the shin" , "One has a cap" , "Lower limb joint" .)