Fail to mention Crossword Clue

 The answer to the crossword clue "Fail to mention" is OMIT.

To omit means to leave out or leave undone. It can also mean to neglect or disregard.

Here are some examples of how the word "omit" might be used in a sentence:

The historian omitted several important facts from her account.

The teacher omitted the difficult chapter from the syllabus.

The recipe omitted a key ingredient.

"Omit" is often used in crossword puzzles because it is a relatively short word that can fit into a variety of different grids. It is also a fairly common word, so it is likely to be familiar to solvers.

I hope this helps!