临危 is a verb-object compound meaning 'to face imminent danger or deadly peril'. It is often used in formal or literary contexts and appears in fixed phrases like 临危不惧 (fearless in the face of danger) and 临危受命 (entrusted with a mission at a critical juncture). Although labeled as a separable verb (离合词), it is rarely split in modern Chinese; learners should treat it as a fixed verb.