Let heat sort out a sportsman (7)
I believe the answer is:
athlete
'a sportsman' is the definition.
(type of sportsman)
'let heat sort out' is the wordplay.
'sort out' is an anagram indicator.
'let'+'heat'='letheat'
'letheat' with letters rearranged gives 'ATHLETE'.
(Other definitions for athlete that I've seen before include "Announces impending danger" , "One who's good at sport" , "Trained sportsperson" , "One may run" , "One trained to compete in sports" .)