如臨大敵

如临大敌
lín
  1. lit. as if meeting a great enemy (idiom)
  2. fig. cautious
  3. with great preoccupation
  4. with strict precaution

CEDICT

to have strict precautions; to be overly critical of the current situation

Wiktionary

好像面對強大敵人一樣比喻戒備森嚴或將事情得很嚴重

重編國語辭典

Entry Composition