Violent criminal’s secure telephone (4-6)

I believe the answer is:

safe-blower

'violent criminal's' is the definition.
(someone who blows up safes)

'secure telephone' is the wordplay.
'secure' becomes 'safe' (similar in meaning).
'telephone' becomes 'blower' (blower can informally mean the telephone).
'safe'+'blower'='SAFE-BLOWER'

(Another definition for safe-blower that I've seen is " Thief using explosives".)

I've seen this clue in The Times.

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