Give up or renounce the throne (8)
I believe the answer is:
abdicate
This clue is a double definition.
'give up' is the first definition.
(abdicating is a kind of giving up)
'renounce the throne' is the second definition.
(I've seen this before)
(Other definitions for abdicate that I've seen before include "Give up rule" , "Give up power" , "Leave throne" , "Give up a throne" , "Abandon" .)