Warmth (4)
'warmth' is the definition.
(synonyms)
This is all the clue.
(Other definitions for heat that I've seen before include "Energy that causes a rise in temperature" , "eliminating round" , "Warmth - gossip mag" , "Apply warmth" , "Level of spice" .)
(Other definitions for temperature that I've seen before include "Degree of hotness" , "Measure of heat" , "Degree of heat" , "Measure of warmth" .)