The most common and most likely answer to this crossword clue is the 2 plus 4 letter word NO FEAR
I've seen this crossword clue in The Guardian
N
O
F
E
A
R
More clues leading to the result NO FEAR
- Certainly not name of listener
- Never what the bold show
- Part reduction of earnings? Definitely not!
- Nerves of steel? I think not!
- Approach grasping old fellow? Definitely not!
- … a brave statement, certainly
- Always brave? Not likely!
- Certainly not/ what intrepid person has
- Name of organ — forget it!
- Certainly not included in population of Earth
Buddy explains!

The straight part
We know that "forget it!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case forget it! = no fear.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.