Heralding what could make air show end — fog (13)
I believe the answer is:
foreshadowing
'heralding' is the definition.
The definition and answer can be both to do with communicating as well as being present participle verbs.
Maybe they are linked in a way I don't understand?
'could make air show end fog' is the wordplay.
'could make' is an anagram indicator.
'air'+'show'+'end'+'fog'='airshowendfog'
'airshowendfog' with letters rearranged gives 'FORESHADOWING'.
'what' is the link.
Can you help me to learn more?
(Another definition for foreshadowing that I've seen is " Being an indication (of something to follow)".)