Understand refusal must mean hell (7)

I believe the answer is:

inferno

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'must mean hell' is the definition.
'inferno' can be an answer for 'hell' (inferno can mean hell as in Dante's Inferno). I am unsure of the 'must mean' bit.

'understand refusal' is the wordplay.
'understand' becomes 'infer' (synonyms).
'refusal' becomes 'no'.
'infer'+'no'='INFERNO'

Can you help me to learn more?

(Other definitions for inferno that I've seen before include "Fierce fire" , "blazer?" , "Dante's scene of horror" , "hot spot" , "(Fiery) Hell" .)

I've seen this clue in The Telegraph.

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