Important fluid, fool made into a coagulated mass (5,4)

I believe the answer is:

blood clot

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'a coagulated mass' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'important fluid fool' is the wordplay.
'important fluid' becomes 'blood' (I have seen 'Red fluid' mean 'blood' so perhaps 'fluid' could also mean 'blood'. I am not sure about the 'important' bit.).
'fool' becomes 'clot' (I've seen this before).
'blood'+'clot'='BLOOD CLOT'

'made into' is the link.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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