The team is looking to 'defend' its national title. [=to win the national title again]
As a U.S. senator, it is my responsibility to 'defend' [='uphold'] the Constitution.
She successfully 'defended' her championship. [=she won the championship again]
(..) Absolutely. ''Yes'' is a comfort. ''Absolutely'' is not. Let me tell you about winds. There is a, a whirlwind from southern Morocco the Aajej against which the Fellahin defend themselves with knives. And there is a a Ghibli from Tunis. - A Ghibli? - A Ghibli. (..)1996 The English Patient