The most common and most likely answer to this crossword clue is the 6 letter word UNBORN
I've seen this crossword clue in The Guardian
U
N
B
O
R
N
Buddy explains!

The straight part
We know that "yet to come /yet to come" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case yet to come /yet to come = unborn.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.
What does UNBORN mean?
UNBORN noun- A single unborn offspring at any stage of gestation.
- Unborn offspring collectively.
- Not yet born; yet to come; future.
- Not yet delivered; still existing in the mother's womb.
- Existing without birth or beginning.