if you scratch the surface of a subject or a problem, you only discover or deal with a very small part of it.

Up to now newspaper articles have only scratched the surface of this tremendously complex issue. (usually + of)

• spill your guts
• spin doctor
• spin in grave
• spin in someone's grave
• spin off
• spin off something
• spin out
• spin out something
• spin wheels
• spin your wheels
• spirit moves
• spirit moves you
• spit and polish
• spit-and-sawdust
• spit blood
• spit nails
• split hairs
• split sides
• split sides laughing
• split the difference
• split your sides
• split your sides laughing
• spoiling for a fight
• spoil rotten
• spoil someone rotten