Like the change in your pocket (5)
I believe the answer is:
small
'pocket' is the definition.
The definition and answer can be both body parts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for small that I've seen before include "Young; modest" , "Of no great size" , "Tiny" , "tiddly" , "of little significance" .)