Phrasal verbs are two or more words that come together to give us a new verb with a different meaning from the original words.
Phrasal Verb:
tighten up
Meaning / Example:
1. [for something] to get tighter. > The door hinges began to tighten up, making the door hard to open and close.
2. [for someone or a group] to become miserly. > The government tightened up and our budget was slashed. > We almost went out of business when we couldn't get credit because the bank tightened up.
3. [for someone or something] to become more restrictive. > The boss is tightening up on new hiring.