The most common and most likely answer to this crossword clue is the 11 letter word COOPERATIVE
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "Helpfu" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case helpfu = cooperative.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 COOPERATIVE mean?
COOPERATIVE noun- A type of company that is owned partially or wholly by its employees, customers or tenants.
- Ready to work with another person or in a team; ready to cooperate.
- Involving cooperation between individuals or parties.
- Relating to a cooperative or cooperatives.