Just a line to say there’s going to be a merger (6)
I believe the answer is:
hyphen
'merger' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for hyphen that I've seen before include "Punctuation mark separating words" , "Dash breaking word" , "A horizontal words-joiner" , "A horizontal word-joiner" , "It joins two words" .)