Unattended criminal on edge, to an extent (5)

I believe the answer is:

alone

'unattended' is the definition.
(similar in meaning)

'criminal on edge to an extent' is the wordplay.
'to an extent' says the answer is hidden in the clue.
'ALONE' is hidden within 'criminal on edge'.

(Other definitions for alone that I've seen before include "Isolated; exclusively" , "without partner?" , "Singly" , "With no one to see" , "Single" .)

I've seen this clue in The Telegraph.

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