Copper-plated coin (4)
I believe the answer is:
cent
'copper-plated coin' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cent that I've seen before include "One tenth of a dime" , "One-hundredth of the value of the basic unit" , "cheap at this price?" , "One hundreth of a dollar" , "Fractional monetary unit" .)