败阵 is a separable verb (离合词) meaning 'to be defeated in a battle or contest'. The two syllables 败 and 阵 can be separated by inserting a measure word, duration, or complement between them, as in 败了三次阵 ('was defeated three times'). The object of the competition is typically introduced with 在...中 or 在...上, not placed after the whole word. You'll hear it in both literal military contexts and figurative competition settings.