Learn what is less than heartening (4)

I believe the answer is:

hear

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'learn' is the definition.
(I know that learn can be written as hear)

I can't explain the remainder of the clue.

(Other definitions for hear that I've seen before include "Listen to" , "Perceive audibly" , "Discover aurally" , "Pick up, aurally" , "receive information" .)

I've seen this clue in the Evening Standard.

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