The heat in a strange room (5)
I believe the answer is:
anger
'the heat' is the definition.
(I've seen this in another clue)
'in a strange room' is the wordplay.
'in' indicates a hidden word.
'ANGER' is hidden in the letters of 'strange room'.
(Other definitions for anger that I've seen before include "Strong displeasure" , "Great annoyance" , "Emotion" , "Hack off" , "Strongly annoy" .)