Soften the mood? (6)
I believe the answer is:
temper
I believe this clue is a double definition.
'soften' is the first definition.
(I've seen this in another clue)
'mood?' is the second definition.
(temper is one's mood or state of mind)
'the' is the link.
(Other definitions for temper that I've seen before include "Harden metal by heating and cooling" , "Moderate - mood" , "Mood or hardness of metal" , "Modify" , "Frame of mind" .)