Copper, maybe, from east allowed to imprison people (7)
I believe the answer is:
element
'copper maybe' is the definition.
(copper is a chemical element)
'east allowed to imprison people' is the wordplay.
'east' becomes 'e' (abbreviation).
'allowed to' becomes 'let' (to let something happen is to allow it).
'imprison' indicates putting letters inside.
'people' becomes 'men' (men are people).
'let' enclosing 'men' is 'lement'.
'e'+'lement'='ELEMENT'
'from' acts as a link.
(Other definitions for element that I've seen before include "Ingredient - small amount" , "Iron, for instance - part of an electric kettle" , "Eg copper" , "eg Fire, air" , "Chemical building-block" .)