Look for getting high, inhaling new joints … (5)
I believe the answer is:
knees
'joints' is the definition.
(knee is a kind of joint)
'look for getting high inhaling new' is the wordplay.
'look for' becomes 'seek' ('seek' can be a synonym of 'look for').
'getting high' says the letters should be written in reverse (in a down clue, letters go up).
'inhaling' means one lot of letters goes inside another.
'new' becomes 'n'.
'seek' back-to-front is 'kees'.
'kees' placed around 'n' is 'KNEES'.
(Other definitions for knees that I've seen before include "Leg joints" , "Lap" , "Legs' joints" , "Hinge joints" , "Hinged joints" .)