Fool in rage about uncontrolled heat (7)
I believe the answer is:
fathead
'fool' is the definition.
(fathead is a kind of fool)
'rage about uncontrolled heat' is the wordplay.
'rage' becomes 'fad' ('fad' can be a synonym of 'rage'**).
'about' is an insertion indicator.
'uncontrolled' indicates anagramming the letters.
'heat' anagrammed gives 'thea'.
'fad' going around 'thea' is 'FATHEAD'.
'in' is the link.
(Other definitions for fathead that I've seen before include "silly ass!" , "Slang idiot with enlarged cranium?" , "Charlie" , "Fool" , "Stupid person" .)