(entered for 12.29.05)

Meaning: only the most visible part of a much bigger whole. Use examples.
Rewrite 1: just a jewel of a buried treasure
Rewrite 2: only a penny of a pocketful of change
Rewrite 3: just the street entrance of a 40-storynoun3 building
Rewrite 4: but the flower of a long-rooted dandelion

Comment: I first established a larger whole then decribed on a smaller part; it helps to stick with something most people would recognize rather than something more obscure, although if you’re addressing a special audience you can most certainly pick an object perhaps known mostly or only to them.

More reading about clichés
What I found when I googled “clichés”:
• Colonial Clichés in a German Zoo? “Many zoos put on special exhibits in order to attract visitors. Most also attract little notice much less controversy. But one zoo in southern Germany is…”