Restrained, cut line in second edition (8)

I believe the answer is:

shackled

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'restrained' is the definition.
(shackling is a kind of restraining)

'cut line in second edition' is the wordplay.
'cut' becomes 'hack' (hack can mean to cut or chop).
'line' means one lot of letters goes inside another.
'in second edition' becomes 'sled' (I am not sure about this - if you are sure you should believe this answer much more).
'hack' placed into 'sled' is 'SHACKLED'.

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(Other definitions for shackled that I've seen before include "In chains" , "Restrained" , "Confined, as with fetters" .)

I've seen this clue in The Guardian.

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