Spare weapon?

I believe the answer is:

spear

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'weapon?' is the definition.
(spear is a kind of weapon)

'spare' is the wordplay.
'spare' can be anagrammed to 'SPEAR'.
Though, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for spear that I've seen before include "Spike" , "asparagus for example" , "Pole with pointed end" , "pierce with this?" , "Portion of asparagus" .)

I've seen this clue in the Evening Standard.

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