Scale getting hot in a fire then exploded (10)
I believe the answer is:
fahrenheit
'scale' is the definition.
(Fahrenheit temperature scale)
'hot in a fire then exploded' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'in' means one lot of letters goes inside another.
'exploded' is an anagram indicator.
'a'+'fire'+'then'='afirethen'
'afirethen' anagrammed gives 'farenheit'.
'h' going within 'farenheit' is 'FAHRENHEIT'.
'getting' is the link.
(Other definitions for fahrenheit that I've seen before include "Man of some scale" , "Measure of warmth" , "In which one can express warmth" , "Finer heath (anag.)" , "Physicist; temperature scale" .)