The most common and most likely answer to this crossword clue is the 5 letter word GRIMM
I've seen this crossword clue in Financial Times
G
R
I
M
M
More clues leading to the result GRIMM
- Formidable sounding tale-teller
- Stern-sounding fairytale brothers
- One of two story-tellers, awful to listen to
- Serious about married brothers
- Good writer’s opening room for another one
- Harsh-sounding brother
- Terrible end of term for taletellers
- Brother-in-lore?
- Story-teller sounds ghastly
- Author audiobook confuses with Sterne?
Buddy explains!

The straight part
We know that "One of two story-tellers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one of two story-tellers = grimm.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.