Prompter, if traffic jam reported? (7)
I believe the answer is:
autocue
'prompter' is the definition.
(I know that prompter can be written as autocue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for autocue that I've seen before include "Hidden screen showing the script to a speaker" , "TV presenter's line-feeder" , "TV prompter" , "Newsreader's aid" , "TV prompt machine" .)