Hard material — too hard, we fancy (9)

I believe the answer is:

heartwood

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'hard material' is the definition.
'heartwood' can be an answer for 'material' (heartwood is a kind of material). I am not sure about the 'hard' bit.

'too hard we fancy' is the wordplay.
'fancy' indicates anagramming the letters.
'too'+'hard'+'we'='toohardwe'
'toohardwe' is an anagram of 'HEARTWOOD'.

Can you help me to learn more?

(Another definition for heartwood that I've seen is " hard stuff".)

I've seen this clue in The Times.

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