Developing roots or trunk (5)
I believe the answer is:
torso
'trunk' is the definition.
(both can mean a person's chest)
'developing roots' is the wordplay.
'developing' indicates an anagram (letters developed into a new form).
'roots' is an anagram of 'TORSO'.
'or' is the link.
(Other definitions for torso that I've seen before include "Body's trunk" , "Chest" , "Trunk; headless, limbless body" , "Body's core" , "Poorly-dressed child" .)