Decline to give up (4)
I believe the answer is:
drop
I believe this is a double definition.
'decline' is the first definition.
(dropping is a kind of declining)
'give up' is the second definition.
(dropping is a kind of giving up)
'to' acts as a link.
(Other definitions for drop that I've seen before include "Fall; abandon" , "to omit the > smallest amount" , "See 1" , "Plummet" , "Dispense with - sink" .)