Thin spears can break (6)

I believe the answer is:

sparse

I'm a little stuck... Click here to teach me more about this clue!

'thin' is the definition.
(synonyms)

'spears can break' is the wordplay.
'spears' anagrams to 'SPARSE'.
But, I am unsure how this is indicated.

Can you help me to learn more?

(Other definitions for sparse that I've seen before include "In short supply" , "Thinly spread" , "Thinly-spread" , "Infrequent" , "Thinly dispersed" .)

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