Promise extreme hardship (6)
I believe the answer is:
plight
This could be a double definition.
'promise extreme' is the first definition.
'plight' can be an answer for 'promise' (plighting is a kind of promising). I am unsure of the 'extreme' bit.
'hardship' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for plight that I've seen before include "Serious predicament" , "Jam" , "Alarming predicament" , "Unfortunate situation" , "Predicament, difficulty" .)