Police are ___________ drug dealers.

• Crack down on something: [phrasal verb]
English meaning: to start dealing with bad or illegal behaviour in a more severe way.
Bangla meaning: কারো বিরুদ্ধে শৃঙ্খলামূলক শাস্তির ব্যবস্থা করা।

Example sentence:
- The library is cracking down on people who lose their books.
- He campaigned earnestly, promising to crack down on street crime.

Complete sentence: Police are cracking down on drug dealers.

Source: Cambridge & Accessible Dictionary.