Penny's worth (4)
I believe the answer is:
cent
'penny's worth' 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 "Small American coin" , "One-hundredth of the basic monetary unit" , "One tenth of a dime" , "cheap at this price?" , "Little bit of money" .)