You won't get much change out of her! (5)
I believe the answer is:
penny
'her' is the definition.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for penny that I've seen before include "Little bit of 18" , "One hundredth of a pound" , "Smallest UK coin" , "Copper coin" , "Lancaster" .)