Roots forming the trunk (5)
I believe the answer is:
torso
'trunk' is the definition.
(both can mean a person's chest)
'roots forming' is the wordplay.
'forming' indicates an anagram.
'roots' is an anagram of 'TORSO'.
'the' is the link.
(Other definitions for torso that I've seen before include "Poorly-dressed child" , "Trunk of human body" , "part of body will be found" , "Body, minus its head and limbs" , "Main part of human body" .)