An SOS about top domestic hazard (8)

I believe the answer is:

asbestos

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'domestic hazard' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'an sos about top' is the wordplay.
'an' becomes 'a'.
'about' indicates putting letters inside.
'top' becomes 'best' (associated in meaning).
'sos' enclosing 'best' is 'sbestos'.
'a'+'sbestos'='ASBESTOS'

Can you help me to learn more?

(Other definitions for asbestos that I've seen before include "Insulating mineral" , "dangerous dust" , "Fibrous insulation material, dangerous to health" , "Fire-resistant mineral" , "Fibrous material, doesn't burn" .)

I've seen this clue in The Sun.

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