Temperature, approximately, for body part (5)
I believe the answer is:
torso
'body part' is the definition.
('torso' is part of 'body')
'temperature approximately' is the wordplay.
'temperature' becomes 't' (abbreviation).
'approximately' becomes 'orso' ('or so' can be a synonym of 'approximately').
't'+'orso'='TORSO'
'for' is the link.
(Other definitions for torso that I've seen before include "Main part of human body" , "upper body" , "Trunk; headless, limbless body" , "Chest" , "Piece of bronze" .)