Severe mental distress (7)
I believe the answer is:
anguish
'severe mental distress' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for anguish that I've seen before include "Angst" , "Mental torment" , "Severe pain, may be mental" , "Hi, Angus - that hurts" , "Grief" .)