Meaning: Make something straight
Example: I'm always having to STRAIGHTEN OUT the wires connected to my computer.
Meaning: Deal with a problem
Example: I had to STRAIGHTEN OUT things after the mess they had made.
Meaning: Make clear and resolve
Example: There are a few issues I'd like to STRAIGHTEN OUT first.
Meaning: Improve someone's behaviour
Example: Starting work has STRAIGHTENED him OUT and calmed him down.
We have 2 phrasal verbs with 'STRAIGHTEN'