Promised W-H-E-A-T (5)
I believe the answer is:
spelt
'promised' is the definition.
The answer and definition can be both to do with communicating as well as being past participle verbs.
Maybe there's an association between them I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spelt that I've seen before include "An old type of wheat" , "grain" , "Inferior species of wheat" , "cereal" , "Made up a word" .)