Detest boiling heat (4)
I believe the answer is:
hate
'detest' is the definition.
(synonyms)
'boiling heat' is the wordplay.
'boiling' indicates an anagram.
'heat' anagrammed gives 'HATE'.
(Other definitions for hate that I've seen before include "[OPPOSITE OF] Be besotted with" , "Loathing" , "Despise" , "Strong aversion" , "Antipathy" .)