Draw round new body part (4)
I believe the answer is:
lung
'body part' is the definition.
(lung is a kind of body part)
'draw round new' is the wordplay.
'draw' becomes 'lug' (I can't explain this - if you can you should believe this answer much more).
'round' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'lug' enclosing 'n' is 'LUNG'.
Can you help me to learn more?
(Other definitions for lung that I've seen before include "Of sound mind" , "Organ providing oxygen to the blood" , "breather" , "Pulmonary organ" , "Breathing apparatus" .)