Temperature, approximately, in the trunk (5)
I believe the answer is:
torso
'trunk' is the definition.
('torso' can be a synonym of 'trunk')
'temperature approximately' is the wordplay.
'temperature' becomes 't' (abbreviation).
'approximately' becomes 'orso' ('or so' can be a synonym of 'approximately').
't'+'orso'='TORSO'
'in the' is the link.
(Other definitions for torso that I've seen before include "Roost (anag)" , "Roost on trunk?" , "unfinished work" , "Body, minus its head and limbs" , "part of body will be found" .)