Part of chest or solid trunk (5)
I believe the answer is:
torso
'trunk' is the definition.
('torso' can be a synonym of 'trunk')
'part of chest or solid' is the wordplay.
'part of' indicates a hidden word.
'TORSO' is hidden in the letters of 'chest or solid'.
(Other definitions for torso that I've seen before include "Trunk of human body" , "Body, minus its head and limbs" , "Limbless statue" , "upper body" , "Body without head, neck and limbs" .)