Bolt one’s cell, back in prison (8)
I believe the answer is:
dartmoor
'prison' is the definition.
(English prison)
'bolt one's cell back' is the wordplay.
'bolt' becomes 'd'art' (I've seen this in another clue).
'one's cell' becomes 'room' (I can't explain this - if you can you should give a lot more credence to this answer).
'back' says the letters should be written backwards.
'room' backwards is 'moor'.
'dart'+'moor'='DARTMOOR'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for dartmoor that I've seen before include "National Park in Devon" , "place of H [HORSE]" , "Devon pony breed" , "Can people spend a lot of time here" , "Well-known prison in Devon" .)