Order is Gallic about energy that keeps things dry (6,3)

I believe the answer is:

silica gel

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'order is gallic about energy that keeps things dry' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'order is gallic about energy' is the wordplay.
'order' indicates an anagram.
'about' is an insertion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'is'+'gallic'='isgallic'
'isgallic' with letters rearranged gives 'silicagl'.
'silicagl' placed around 'e' is 'SILICA GEL'.

Can you help me to learn more?

(Another definition for silica gel that I've seen is " drier".)

I've seen this clue in The Daily Express.

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