Just the blockhead to say something soft (6)
I believe the answer is:
butter
'say something soft' is the definition.
I can't tell whether this defines the answer.
'just the blockhead' is the wordplay.
'just' becomes 'but' (I've seen this in other clues).
'the blockhead' becomes 'ter' (I am not sure about this - if you are sure you should believe this answer much more).
'but'+'ter'='BUTTER'
'to' is the link.
Can you help me to learn more?
(Other definitions for butter that I've seen before include "If it wouldn't melt in your mouth, you're innocent" , "Milk product" , "Process of instruction" , "Fat - type of fly" , "Solid fat churned from milk" .)