One kills when SAS stray from path (8)

I believe the answer is:

assassin

'one kills' is the definition.

'when sas stray from path' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'stray from path' becomes 'sin'.
'as'+'sas'+'sin'='ASSASSIN'

(Other definitions for assassin that I've seen before include "Professional, often political, killer" , "Booth, for example" , "One making hits" , "Hired murderer" , "Hitman" .)

I've seen this clue in The Sun.

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