鑿壁偷光 [凿－－－]

Jyutping zok6 bik1 tau1 gwong1
Pinyin záo bì tōu guāng

Definitions (CC-CEDICT)
  1. lit. to pierce the wall to steal a light (idiom)
  2. fig. to study diligently in the face of hardship
Definitions (粵典–words.hk)
  1. 語句
    刻苦​勤學
    to study very diligently