Extremely clean and a lot faster? I'll say! (7)

I believe the answer is:

sterile

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'extremely clean' is the definition.
'sterile' can be an answer for 'clean' (I've seen this before). I am not sure about the 'extremely' bit.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for sterile that I've seen before include "Like theatre" , "Unable to have children" , "Pointless" , "Aseptic or infertile" , "Unable to produce young" .)

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

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