笛
テキ, ふえ, う
flute, clarinet, pipe, whistle, bagpipe, piccolo
JLPT1 G3 S11 F1928
As per
由
# (pass/run through) +
竹
(rigid, tubular) bamboo → *flute/pipe* (← cylindrical instruments through which sound passes) → *whistle*.
[Full Kanji Etymology List]