Asiatic cooks taking cocaine for painful condition (8)
I believe the answer is:
sciatica
'painful condition' is the definition.
'asiatic cooks taking cocaine' is the wordplay.
'cooks' indicates anagramming the letters.
'taking' means one lot of letters goes inside another.
'cocaine' becomes 'C' (drugs abbreviation).
'asiatic' anagrammed gives 'siatica'.
'siatica' enclosing 'c' is 'SCIATICA'.
'for' is the link.
(Other definitions for sciatica that I've seen before include "Lower back and hip pain" , "Form of neuralgia" , "Disorder around the hip" , "Type of neuritis" , "Neuralgia of the hip and thigh" .)