High temperature changed, with the keys inside (5,4)
I believe the answer is:
white heat
'high temperature' is the definition.
(white heat is a kind of high temperature)
'changed with the keys inside' is the wordplay.
I cannot really understand how this works, but
an anagram of 'with' is 'whit' which is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for white heat that I've seen before include "Glowing temperature" , "intense temperature" .)