Some relief for visually impaired? (7)

I believe the answer is:

braille

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'some relief' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for braille that I've seen before include "Liberal (anag) - reading system" , "Bumps felt" , "Writing system for the blind" , "Raised type for blind people" , "Points raised" .)

I've seen this clue in The Telegraph.

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