The most common and most likely answer to this crossword clue is the 5 letter word IOTAS
I've seen this crossword clue in The Guardian
I
O
T
A
S
More clues leading to the result IOTAS
- Is it as one originally maintained?
- Day I flipped over love letters
- Very small bits of moon visible before day is over
- Jots heading down in strange patois
- Jots ideas on tablet, absently scribbling initially
- Foreign characters given one endless job, receiving nothing
- Periodically, iron traps particles
- One cooking oats and grains
- KrisKross shredded oats to small pieces
- Radicchio tastes good in little bits.
Buddy explains!

The straight part
We know that "Is" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case is = iotas.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 IOTAS mean?
IOTAS noun- The ninth letter of the Greek alphabet.
- A jot; a very small, insignificant quantity.