Converting current to energy, entirely transformed material (8)

I believe the answer is:

terylene

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'material' is the definition.
(Terylene is an example)

I can't explain the remainder of the clue.

(Other definitions for terylene that I've seen before include "Fabric of polyester fibres" , "synthetic stuff" , "Synthetic material" , "Synthetic fibre" , "Crease-resistant fibre" .)

I've seen this clue in The Times.

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