Temperature on flat earth? (6)
I believe the answer is:
planet
'earth?' is the definition.
(Earth is an example)
'temperature on flat' is the wordplay.
'temperature' becomes 't' (abbreviation).
'on' means one lot of letters go next to another.
'flat' becomes 'plane' (I've seen this before).
't' put after 'plane' is 'PLANET'.
(Other definitions for planet that I've seen before include "Jupiter is one" , "Heavenly body moving round the sun" , "Is Pluto one?" , "One orbiting star" , "Eg, a ruby" .)