Sack people – they can go to blazes! (7)

I believe the answer is:

firemen

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'they can go to blazes' is the definition.
The definition suggests an adverb but the answer is not.

'sack people' is the wordplay.
'sack' becomes 'fire' ('fire' can be a synonym of 'sack').
'people' becomes 'men' (man is a kind of person).
'fire'+'men'='FIREMEN'

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(Other definitions for firemen that I've seen before include "Stokers" , "Hose wielder" , "Their job is to extinguish conflagrations" , "They fight conflagrations" .)

I've seen this clue in the Evening Standard.

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