The most common and most likely answer to this crossword clue is the 9 letter word ACCESSORY
I've seen this crossword clue in The Guardian
A
C
C
E
S
S
O
R
Y
More clues leading to the result ACCESSORY
- Starts to stir up serious trouble out of a success story? That’s helpful!
- Additional item that could be charged
- Trapping criminal associate?
- Confederate soldiers observed by Yankee behind entrance
- Say soccer preparation is extra
- Endless road? Timeless record is fitting
- Henchman’s entry into Labour Party at last
- Additional individual abetting criminal
Buddy explains!

The straight part
We know that "That’s helpful" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that’s helpful = accessory.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 ACCESSORY mean?
ACCESSORY adjective- Having a secondary, supplementary or subordinate function by accompanying as a subordinate; aiding in a secondary way; being additional; being connected as an incident or subordinate to a principal; contributing or being contributory. Said of people and things, and, when of people, usually in a bad sense
- Assisting a crime without actually participating in committing the crime itself.
- Present in a minor amount, and not essential.
- Something that belongs to part of another main thing; something additional and subordinate, an attachment.
- An article that completes one's basic outfit, such as a scarf or gloves.
- A person who is not present at a crime, but contributes to it as an assistant or instigator.
- Something in a work of art without being indispensably necessary, for example solely ornamental parts.