Body temperature on surface (6)
I believe the answer is:
planet
'body' is the definition.
(I have seen 'Celestial body' mean 'planet' so perhaps 'body' could also mean 'planet')
'temperature on surface' is the wordplay.
I cannot quite see how this works, but
'temperature' could be 't' (abbreviation) and 't' is located in the answer.
'surface' could be 'plane' (I've seen this before) and 'plane' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for planet that I've seen before include "One orbiting star" , "Sun's orbiter" , "Earth, for instance" , "World" , "Neptune, for example" .)