iron out

Short definition from Wiktionary

Verb

1. 1
   To remove (a crease or creases) with an iron.
2. 2
   To make (something) flat or smooth as if with an iron.
3. 3
   To resolve (a dispute); to solve (a problem).
4. 4
   To thrash or beat up; to overwhelm in a fight.
5. 5
   To kill.