Three notes, usually nice and soft (3)
I believe the answer is:
bed
'usually nice and soft' is the definition.
I can't tell whether this defines the answer.
'three notes' is the wordplay.
'three notes' means three replacements for 'note'.
'note' becomes 'b' (musical note).
'note' becomes 'e' (musical note).
'note' becomes 'd' (musical note).
'b'+'e'+'d'='BED'
Can you help me to learn more?
(Other definitions for bed that I've seen before include "In which to place the body of flowers" , "Place for plants and sleep" , "might be laid here" , "Plot in which plants are growing" , "pit" .)