1. Make clear and (more) comprehensible
   "clear up the mystery surrounding her death";
   - clarify, elucidate
    
2. Make clear or more understandable; remove confusion or ambiguity
   "Clear up the question of who is at fault";
   - clear, shed light on, crystallize, crystallise [Brit], crystalize [US, rare], straighten out, sort out, enlighten, illuminate, elucidate
    
3. Become free from clouds or less cloudy; become brighter
   "The sky cleared up after the storm";
   - clear, light up, brighten
    
4. Heal or disappear (of a medical condition)
   "Her skin rash cleared up after using the cream"
    
5. Tidy or put in order
   "Let's clear up this mess before guests arrive"

Derived forms: clears up, clearing up, cleared up

Type of: alter, change, explain, explicate, vary