clear up
phr. v..phr. v.. to solve a problem or explain a misunderstanding; it can also mean that the weather becomes sunny or a skin problem goes away.
phr. v.. to resolve a confusion or mystery; intransitively, to describe the dissipation of clouds or the healing of a medical condition like a rash.
I hope the weather clears up before our picnic.
We need to have a meeting to clear up any confusion about the new project rules.
The doctor prescribed an ointment that should clear up the infection within a few days, provided the patient follows the application schedule.
when used for problems or misunderstandings, it usually takes a direct object.
this is a polysemous phrasal verb; use a 'weather vs. problem' matching activity to help students distinguish between the intransitive and transitive uses.
The rain cleared up the sky.The sky cleared up.when talking about weather, 'clear up' is usually intransitive and the sky or weather is the subject, not the object.