Pothead skinned knee in brief rage (6)
I believe the answer is:
stoner
'pothead' is the definition.
(both can mean a drug user)
'skinned knee in brief rage' is the wordplay.
'skinned' says to take the centre.
'in' indicates putting letters inside.
'brief rage' becomes 'stor' (I am not sure about this - if you are sure you should believe this answer much more).
The central letters of 'knee' are 'ne'.
'ne' inserted inside 'stor' is 'STONER'.
Can you help me to learn more?
(Other definitions for stoner that I've seen before include "No rest (anag) - cannabis user" , "Slang for habitual pot-smoker" , "Slang for habitual smoker of cannabis" .)