Bolt or lock the cell door to prevent it (6)

I believe the answer is:

escape

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'bolt' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for escape that I've seen before include "Get away from depravity" , "Elude; leakage" , "'Break free, get away (6)'" , "An outburst" , "Gain freedom" .)

I've seen this clue in The Globe and Mail, The Telegraph and The Guardian.

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