Hate to run a preliminary race (4)
I believe the answer is:
heat
'a preliminary race' is the definition.
(I've seen this in another clue)
'hate to run' is the wordplay.
'to run' indicates anagramming the letters.
'hate' with letters rearranged gives 'HEAT'.
(Other definitions for heat that I've seen before include "Provide warmth" , "Energy that caues a rise in temperature" , "Pressure" , "Toast" , "Energy that causes a rise in temperature" .)