The most common and most likely answer to this crossword clue is the 7 letter word ASSAGAI
I've seen this crossword clue in The Guardian
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More clues leading to the result ASSAGAI
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The straight part
We know that "Spear" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spear = assagai.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 ASSAGAI mean?
ASSAGAI noun- A slim hardwood spear or javelin with an iron tip, especially those used by Bantu peoples of Southern Africa.
- The tree species Curtisia dentata, the wood of which is traditionally used to make assegais.
- To spear with an assegai.