The most common and most likely answer to this crossword clue is the 11 letter word DISPENSABLE
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The straight part
We know that "Needless" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case needless = dispensable.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 DISPENSABLE mean?
DISPENSABLE adjective- Able to be done without; able to be expended; easily replaced.
- Capable of being dispensed; distributable.
- (of a law, rule, vow, etc.) Subject to dispensation; possible to relax, exempt from, or annul.
- (nutrition, of an amino acid) Not essential to be taken in as part of an organism's diet, as it can be synthesized de novo.