From France, how red alters from now on? (12)

I believe the answer is:

henceforward

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'from now on?' is the definition.
(I've seen this before)

'from france how red' is the wordplay.
'from' indicates anagramming the letters (from the letters).
'france'+'how'+'red'='francehowred'
'francehowred' anagrammed gives 'HENCEFORWARD'.

'alters' acts as a link.
This may not be right. It may be part of another bit of the clue.

Can you help me to learn more?

(Another definition for henceforward that I've seen is " In future".)

I've seen this clue in The Telegraph.

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