Allow to rise, as a remission (3-2)

I believe the answer is:

let-up

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'as a remission' is the definition.
I can't tell whether this defines the answer.

'allow to rise' is the wordplay.
'allow' becomes 'let' (synonyms).
'to rise' becomes 'up' (as a noun).
'let'+'up'='LET-UP'

Can you help me to learn more?

(Other definitions for let-up that I've seen before include "Pause, temporary respite" , "Decline" , "Abatement" , "Respite, relief" , "Relieving pause" .)

I've seen this clue in the Evening Standard.

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