Leave (or again join) regime restricting society (6)
I believe the answer is:
resign
'leave' is the definition.
(I know that vacate is a type of leave office)
'again join regime restricting society' is the wordplay.
I cannot quite see how this works, but
'again' could be 're' (prefix meaning 'again') and 're' is located in the answer.
'society' could be 's' (common abbreviation in names of organisations) and 's' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'or' acts as a link.
Can you help me to learn more?
(Other definitions for resign that I've seen before include "Either leave" , "Leave office voluntarily" , "admit defeat" , "Give up one's job" , "Quit" .)