Pitched battles over marked stones (7)

I believe the answer is:

tablets

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'marked stones' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe there's a link between them I don't understand?

'pitched battles' is the wordplay.
'battles' anagrams to 'TABLETS'.
However, I am unsure how this is indicated.

'over' acts as a link.

Can you help me to learn more?

(Other definitions for tablets that I've seen before include "Battles (anag.)" , "Pellets of medicine" , "Pills" .)

I've seen this clue in the Sydney Morning Herald.

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