Stressful situation -- one shouldn't let off steam (8,6)
I believe the answer is:
pressure cooker
I believe this clue is a double definition.
'stressful situation' is the first definition.
(pressure cooker can mean a high-pressure situation)
'one shouldn't let off steam' is the second definition.
(a pressure cooker cooks using steam pressure)
(Other definitions for pressure cooker that I've seen before include "thing for doing dishes quickly" , "for use in the kitchen" .)