Give up, admit defeat (9)
I believe the answer is:
surrender
I believe this clue is a double definition.
'give up' is the first definition.
(I know that give up can be written as surrender)
'admit defeat' is the second definition.
(to surrender is to admit defeat)
(Other definitions for surrender that I've seen before include "Cede" , "Resign" , "Submit (to an opponent)" , "submission" , "Yield, give in" .)