Very sad or intensely distressing (6)
I believe the answer is:
tragic
This clue is a double definition.
'very sad' is the first definition.
(tragic can mean very sad or unfortunate)
'intensely distressing' is the second definition.
(I've seen this before)
(Other definitions for tragic that I've seen before include "Calamitous, very sad" , "Terribly sad and distressing" , "Pitiable" , "Very sad; Schubert's 4th symphony nickname" , "Deeply distressing" .)