Red stuff in old Roman watering-hole (8)

I believe the answer is:

cinnabar

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'red' is the definition.
(I've seen this before)

'old roman watering-hole' is the wordplay.
'old roman' becomes 'cinna' (Roman politician).
'watering hole' becomes 'bar' (I've seen this before).
'cinna'+'bar'='CINNABAR'

'stuff in' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for cinnabar that I've seen before include "Heavy red mineral containing mercury" , "Red mercury sulphide" , "Bright red mineral containing mercury" , "Brian can make vermilion pigment" .)

I've seen this clue in The Sun.

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