The most common and most likely answer to this crossword clue is the 9 letter word NECESSITY
I've seen this crossword clue in Independent
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More clues leading to the result NECESSITY
- A must to build city with sense
- Essential to reorganise Essen City
- Must it end in tragedy following extraordinary scenes?
- Need change of scene? It’s the Fourth of July!
- Sense city in need of development — that’s a must
- In strange sense, city must, as producer of invention?
- Fundamental precursor to invention
- Frequent need to collect duty, income tax at beginning of the year as obligation
- Southern city seen another way, in crisis
Buddy explains!

The straight part
We know that "Need" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case need = necessity.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 NECESSITY mean?
NECESSITY noun- The quality or state of being necessary, unavoidable, or absolutely requisite.
- The condition of being needy; desperate need; lack
- Something necessary; a requisite; something indispensable.
- Something which makes an act or an event unavoidable; an irresistible force; overruling power
- The negation of freedom in voluntary action; the subjection of all phenomena, whether material or spiritual, to inevitable causation; necessitarianism.
- Greater utilitarian good; used in justification of a criminal act.
- (in the plural) Indispensable requirements (of life).