The last infected pieces of stretchy protein (7)

I believe the answer is:

elastin

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

'stretchy protein' is the definition.
'elastin' can be an answer for 'protein' (elastin is a kind of protein). I am not certain of the 'stretchy' bit.

'the last infected pieces' is the wordplay.
'pieces' says the answer is hidden in the clue (I've seen 'piece of' mean this).
'ELASTIN' is hidden within 'the last infected'.

'of' acts as a link.

Can you help me to learn more?

(Another definition for elastin that I've seen is " protein".)

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

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