Merriam-Webster's Advanced Learner's Dictionary:
deal with [phrasal verb] deal with (someone or something)
1 : to be about (something) : to have (something) as a subject
• The book deals with World War II.
• Her speech dealt with health care and the nation's economy.
• The film deals with some serious issues.
2 : to make business agreements with (someone)
• He deals fairly with all his customers.
• Their salespeople are very easy to deal with.
3 : to do something about (a person or thing that causes a problem or difficult situation)
• The government dealt harshly with the rebels.
• I'll deal with you later.
• Who's going to deal with this mess?
• I dealt with the problem myself.
• Can you suggest some ways of dealing with a difficult child?
• We weren't able/equipped/prepared to deal with such a large crowd of people.
• He needs to learn how to deal with his anger.
4 : to accept or try to accept (something that is true and cannot be changed) : to control your feelings about (something)
• She's still trying to deal with his death.
• I'm still dealing with the fact that we lost the game.
• The weather is bad, but we'll just have to deal with it.
- deal·er noun, pl -ers [count]
• a used car dealer
• drug dealers