Broken treadle had a warning notice (7)
I believe the answer is:
alerted
'had a warning notice' is the definition.
The definition and answer can be both to do with communicating as well as being past participle verbs.
Maybe they are linked in a way I don't understand?
'broken treadle' is the wordplay.
'broken' is an anagram indicator.
'treadle' with letters rearranged gives 'ALERTED'.
Can you help me to learn more?
(Other definitions for alerted that I've seen before include "Put on guard, forewarned" , "Given warning" , "Warned, made aware" , "Related about warning notified" , "Tipped off" .)