Gas maybe the product of identical factors (5)

I believe the answer is:

power

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'product of identical factors' is the definition.
'power' can be an answer for 'product' (I've seen this before). I'm not sure about the 'of identical factors' bit.

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for power that I've seen before include "See 12" , "military force" , "Rate of doing work" , "index" , "Physical strength" .)

I've seen this clue in The Times.

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