下功夫
xià gōng fu · HSK 7
see 下工夫[xia4 gong1 fu5]
🥋 下 (put down) + 功夫 (kung fu / effort) = put in real effort, work hard at it
功夫 is the same word as kung fu: skill earned through effort. 下功夫 literally means to put that effort down onto a task, i.e. to grind away and master it. Same word as 下工夫.
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.
功 — work 工 (phonetic) + strength 力 (semantic)
功 is a semantic-phonetic compound. The right side 力 (strength, a pictograph of a plow or flexed arm) gives the meaning, while 工 (work, originally a carpenter's square) supplies the sound. Together they convey effort applied to work — hence 'achievement, merit, accomplishment.'