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

I believe the answer is:

escape

I'm a little stuck... Click here to teach me more about this clue!

'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 Telegraph, The Guardian and The Globe and Mail.

Want a hint initially instead of a full solution? Install my app