打黑 - Zhictionary

打黑

dǎhēi

to crack down on illegal activities; to fight organized crime

to combat underworld gangs

a semantically light, transitive verb that is combined with various grammatical objects to form compound verbs and verb-object phrases with a diverse range of meanings (e.g. 打傘 dǎsǎn "to hold an umbrella", 打電話 dǎdiànhuà "to make a phone call", 打針 dǎzhēn "to get an injection", 打手套 dǎshǒutào "to knit gloves", 打氣 dǎqì "to inflate")
to hit; to strike
to fight
(coll.) from; since (as in 打那以後 dǎnàyǐhòu "since then")