Collins Chinese Dictionary Plus (3rd edition), 2011:
暗算 ànsuàn 动
plot against
- 他总(總)是暗算别(別)人。 Tā zǒngshì ànsuàn biérén. He's always plotting against people.
- 他常常遭人暗算。 Tā chángcháng zāo rén ànsuàn. He frequently falls prey to other people's machinations.