Sadness, grief (6)
I believe the answer is:
sorrow
I believe this is a double definition.
'sadness' is the first definition.
(I know that sorrow is a type of sadness)
'grief' is the second definition.
(I know that grief can be written as sorrow)
(Other definitions for sorrow that I've seen before include "Sadness; one magpie for it" , "Deep distress" , "Woe" , "'One magpie for ..., two for joy (6)'" , "Expression of grief" .)