expression, ichidan verb
get involved in; start doing; have a hand in
Idiomatic expression meaning to begin engaging in an activity, often one that is new, questionable, or significant. Commonly used with nouns like 仕事, 悪事, or 趣味.
彼は若い頃から政治に手を染めた。
He got involved in politics from a young age.
彼女はつい悪い遊びに手を染めてしまった。
She ended up getting involved in bad pastimes.